Config(3pm) Perl Programmers Reference Guide Config(3pm)

Config - access Perl configuration information

    use Config;
    if ($Config{usethreads}) {
        print "has thread support\n"
    } 
    use Config qw(myconfig config_sh config_vars config_re);
    print myconfig();
    print config_sh();
    print config_re();
    config_vars(qw(osname archname));

The Config module contains all the information that was available to the "Configure" program at Perl build time (over 900 values).

Shell variables from the config.sh file (written by Configure) are stored in the readonly-variable %Config, indexed by their names.

Values stored in config.sh as 'undef' are returned as undefined values. The perl "exists" function can be used to check if a named variable exists.

For a description of the variables, please have a look at the Glossary file, as written in the Porting folder, or use the url: https://github.com/Perl/perl5/blob/blead/Porting/Glossary

Returns a textual summary of the major perl configuration values. See also "-V" in "Command Switches" in perlrun.
Returns the entire perl configuration information in the form of the original config.sh shell variable assignment script.
Like config_sh() but returns, as a list, only the config entries who's names match the $regex.
Prints to STDOUT the values of the named configuration variable. Each is printed on a separate line in the form: 

  name='value';

Names which are unknown are output as "name='UNKNOWN';". See also "-V:name" in "Command Switches" in perlrun.

Returns a list of C pre-processor options used when compiling this perl binary, which affect its binary compatibility with extensions. "bincompat_options()" and "non_bincompat_options()" are shown together in the output of "perl -V" as Compile-time options.
Returns a list of C pre-processor options used when compiling this perl binary, which do not affect binary compatibility with extensions.
Returns the compile date (as a string), equivalent to what is shown by "perl -V"
Returns a list of the names of locally applied patches, equivalent to what is shown by "perl -V".
Returns a list of the header files that should be used as dependencies for XS code, for this version of Perl on this platform.

Here's a more sophisticated example of using %Config:

    use Config;
    use strict;
    my %sig_num;
    my @sig_name;
    unless($Config{sig_name} && $Config{sig_num}) {
        die "No sigs?";
    } else {
        my @names = split ' ', $Config{sig_name};
        @sig_num{@names} = split ' ', $Config{sig_num};
        foreach (@names) {
            $sig_name[$sig_num{$_}] ||= $_;
        }   
    }
    print "signal #17 = $sig_name[17]\n";
    if ($sig_num{ALRM}) { 
        print "SIGALRM is $sig_num{ALRM}\n";
    }

Because this information is not stored within the perl executable itself it is possible (but unlikely) that the information does not relate to the actual perl binary which is being used to access it.

The Config module is installed into the architecture and version specific library directory ($Config{installarchlib}) and it checks the perl version number when loaded.

The values stored in config.sh may be either single-quoted or double-quoted. Double-quoted strings are handy for those cases where you need to include escape sequences in the strings. To avoid runtime variable interpolation, any "$" and "@" characters are replaced by "\$" and "\@", respectively. This isn't foolproof, of course, so don't embed "\$" or "\@" in double-quoted strings unless you're willing to deal with the consequences. (The slashes will end up escaped and the "$" or "@" will trigger variable interpolation)

Most "Config" variables are determined by the "Configure" script on platforms supported by it (which is most UNIX platforms). Some platforms have custom-made "Config" variables, and may thus not have some of the variables described below, or may have extraneous variables specific to that particular port. See the port specific documentation in such cases.

"_a"
From Unix.U:

This variable defines the extension used for ordinary library files. For unix, it is .a. The . is included. Other possible values include .lib.

"_exe"
From Unix.U:

This variable defines the extension used for executable files. "DJGPP", Cygwin and OS/2 use .exe. Stratus "VOS" uses .pm. On operating systems which do not require a specific extension for executable files, this variable is empty.

"_o"
From Unix.U:

This variable defines the extension used for object files. For unix, it is .o. The . is included. Other possible values include .obj.

"afs"
From afs.U:

This variable is set to "true" if "AFS" (Andrew File System) is used on the system, "false" otherwise. It is possible to override this with a hint value or command line option, but you'd better know what you are doing.

"afsroot"
From afs.U:

This variable is by default set to /afs. In the unlikely case this is not the correct root, it is possible to override this with a hint value or command line option. This will be used in subsequent tests for AFSness in the configure and test process.

"alignbytes"
From alignbytes.U:

This variable holds the number of bytes required to align a double-- or a long double when applicable. Usual values are 2, 4 and 8. The default is eight, for safety.

"aphostname"
From d_gethname.U:

This variable contains the command which can be used to compute the host name. The command is fully qualified by its absolute path, to make it safe when used by a process with super-user privileges.

"api_revision"
From patchlevel.U:

The three variables, api_revision, api_version, and api_subversion, specify the version of the oldest perl binary compatible with the present perl. In a full version string such as 5.6.1, api_revision is the 5. Prior to 5.5.640, the format was a floating point number, like 5.00563.

perl.c:incpush() and lib/lib.pm will automatically search in $sitelib/.. for older directories back to the limit specified by these api_ variables. This is only useful if you have a perl library directory tree structured like the default one. See "INSTALL" for how this works. The versioned site_perl directory was introduced in 5.005, so that is the lowest possible value. The version list appropriate for the current system is determined in inc_version_list.U.

"XXX" To do: Since compatibility can depend on compile time options (such as bincompat, longlong, etc.) it should (perhaps) be set by Configure, but currently it isn't. Currently, we read a hard-wired value from patchlevel.h. Perhaps what we ought to do is take the hard-wired value from patchlevel.h but then modify it if the current Configure options warrant. patchlevel.h then would use an #ifdef guard.

"api_subversion"
From patchlevel.U:

The three variables, api_revision, api_version, and api_subversion, specify the version of the oldest perl binary compatible with the present perl. In a full version string such as 5.6.1, api_subversion is the 1. See api_revision for full details.

"api_version"
From patchlevel.U:

The three variables, api_revision, api_version, and api_subversion, specify the version of the oldest perl binary compatible with the present perl. In a full version string such as 5.6.1, api_version is the 6. See api_revision for full details. As a special case, 5.5.0 is rendered in the old-style as 5.005. (In the 5.005_0x maintenance series, this was the only versioned directory in $sitelib.)

"api_versionstring"
From patchlevel.U:

This variable combines api_revision, api_version, and api_subversion in a format such as 5.6.1 (or 5_6_1) suitable for use as a directory name. This is filesystem dependent.

"ar"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the ar program. After Configure runs, the value is reset to a plain "ar" and is not useful.

"archlib"
From archlib.U:

This variable holds the name of the directory in which the user wants to put architecture-dependent public library files for $package. It is most often a local directory such as /usr/local/lib. Programs using this variable must be prepared to deal with filename expansion.

"archlibexp"
From archlib.U:

This variable is the same as the archlib variable, but is filename expanded at configuration time, for convenient use.

"archname"
From archname.U:

This variable is a short name to characterize the current architecture. It is used mainly to construct the default archlib.

"archname64"
From use64bits.U:

This variable is used for the 64-bitness part of $archname.

"archobjs"
From Unix.U:

This variable defines any additional objects that must be linked in with the program on this architecture. On unix, it is usually empty. It is typically used to include emulations of unix calls or other facilities. For perl on OS/2, for example, this would include os2/os2.obj.

"asctime_r_proto"
From d_asctime_r.U:

This variable encodes the prototype of asctime_r. It is zero if d_asctime_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_asctime_r is defined.

"awk"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the awk program. After Configure runs, the value is reset to a plain "awk" and is not useful.

"baserev"
From baserev.U:

The base revision level of this package, from the .package file.

"bash"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"bin"
From bin.U:

This variable holds the name of the directory in which the user wants to put publicly executable images for the package in question. It is most often a local directory such as /usr/local/bin. Programs using this variable must be prepared to deal with ~name substitution.

"bin_ELF"
From dlsrc.U:

This variable saves the result from configure if generated binaries are in "ELF" format. Only set to defined when the test has actually been performed, and the result was positive.

"binexp"
From bin.U:

This is the same as the bin variable, but is filename expanded at configuration time, for use in your makefiles.

"bison"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the bison program. After Configure runs, the value is reset to a plain "bison" and is not useful.

"byacc"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the byacc program. After Configure runs, the value is reset to a plain "byacc" and is not useful.

"byteorder"
From byteorder.U:

This variable holds the byte order in a "UV". In the following, larger digits indicate more significance. The variable byteorder is either 4321 on a big-endian machine, or 1234 on a little-endian, or 87654321 on a Cray ... or 3412 with weird order !

"c"
From n.U:

This variable contains the \c string if that is what causes the echo command to suppress newline. Otherwise it is null. Correct usage is $echo $n "prompt for a question: $c".

"castflags"
From d_castneg.U:

This variable contains a flag that precise difficulties the compiler has casting odd floating values to unsigned long: 0 = ok 1 = couldn't cast < 0 2 = couldn't cast >= 0x80000000 4 = couldn't cast in argument expression list

"cat"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the cat program. After Configure runs, the value is reset to a plain "cat" and is not useful.

"cc"
From cc.U:

This variable holds the name of a command to execute a C compiler which can resolve multiple global references that happen to have the same name. Usual values are "cc" and "gcc". Fervent "ANSI" compilers may be called "c89". "AIX" has xlc.

"cccdlflags"
From dlsrc.U:

This variable contains any special flags that might need to be passed with "cc -c" to compile modules to be used to create a shared library that will be used for dynamic loading. For hpux, this should be +z. It is up to the makefile to use it.

"ccdlflags"
From dlsrc.U:

This variable contains any special flags that might need to be passed to cc to link with a shared library for dynamic loading. It is up to the makefile to use it. For sunos 4.1, it should be empty.

"ccflags"
From ccflags.U:

This variable contains any additional C compiler flags desired by the user. It is up to the Makefile to use this.

"ccflags_uselargefiles"
From uselfs.U:

This variable contains the compiler flags needed by large file builds and added to ccflags by hints files.

"ccname"
From Checkcc.U:

This can set either by hints files or by Configure. If using gcc, this is gcc, and if not, usually equal to cc, unimpressive, no? Some platforms, however, make good use of this by storing the flavor of the C compiler being used here. For example if using the Sun WorkShop suite, ccname will be "workshop".

"ccsymbols"
From Cppsym.U:

The variable contains the symbols defined by the C compiler alone. The symbols defined by cpp or by cc when it calls cpp are not in this list, see cppsymbols and cppccsymbols. The list is a space-separated list of symbol=value tokens.

"ccversion"
From Checkcc.U:

This can set either by hints files or by Configure. If using a (non-gcc) vendor cc, this variable may contain a version for the compiler.

"cf_by"
From cf_who.U:

Login name of the person who ran the Configure script and answered the questions. This is used to tag both config.sh and config_h.SH.

"cf_email"
From cf_email.U:

Electronic mail address of the person who ran Configure. This can be used by units that require the user's e-mail, like MailList.U.

"cf_time"
From cf_who.U:

Holds the output of the "date" command when the configuration file was produced. This is used to tag both config.sh and config_h.SH.

"charbits"
From charsize.U:

This variable contains the value of the "CHARBITS" symbol, which indicates to the C program how many bits there are in a character.

"charsize"
From charsize.U:

This variable contains the value of the "CHARSIZE" symbol, which indicates to the C program how many bytes there are in a character.

"chgrp"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"chmod"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the chmod program. After Configure runs, the value is reset to a plain "chmod" and is not useful.

"chown"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"clocktype"
From d_times.U:

This variable holds the type returned by times(). It can be long, or clock_t on "BSD" sites (in which case <sys/types.h> should be included).

"comm"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the comm program. After Configure runs, the value is reset to a plain "comm" and is not useful.

"compiler_warning"
From compiler_warning.U:

This variable holds the command to check if the file specified as a parameter contains a compiler warning

"compress"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"config_arg0"
From Options.U:

This variable contains the string used to invoke the Configure command, as reported by the shell in the $0 variable.

"config_argc"
From Options.U:

This variable contains the number of command-line arguments passed to Configure, as reported by the shell in the $# variable. The individual arguments are stored as variables config_arg1, config_arg2, etc.

"config_args"
From Options.U:

This variable contains a single string giving the command-line arguments passed to Configure. Spaces within arguments, quotes, and escaped characters are not correctly preserved. To reconstruct the command line, you must assemble the individual command line pieces, given in config_arg[0-9]*.

"contains"
From contains.U:

This variable holds the command to do a grep with a proper return status. On most sane systems it is simply "grep". On insane systems it is a grep followed by a cat followed by a test. This variable is primarily for the use of other Configure units.

"cp"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the cp program. After Configure runs, the value is reset to a plain "cp" and is not useful.

"cpio"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"cpp"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the cpp program. After Configure runs, the value is reset to a plain "cpp" and is not useful.

"cpp_stuff"
From cpp_stuff.U:

This variable contains an identification of the concatenation mechanism used by the C preprocessor.

"cppccsymbols"
From Cppsym.U:

The variable contains the symbols defined by the C compiler when it calls cpp. The symbols defined by the cc alone or cpp alone are not in this list, see ccsymbols and cppsymbols. The list is a space-separated list of symbol=value tokens.

"cppflags"
From ccflags.U:

This variable holds the flags that will be passed to the C pre- processor. It is up to the Makefile to use it.

"cpplast"
From cppstdin.U:

This variable has the same functionality as cppminus, only it applies to cpprun and not cppstdin.

"cppminus"
From cppstdin.U:

This variable contains the second part of the string which will invoke the C preprocessor on the standard input and produce to standard output. This variable will have the value "-" if cppstdin needs a minus to specify standard input, otherwise the value is "".

"cpprun"
From cppstdin.U:

This variable contains the command which will invoke a C preprocessor on standard input and put the output to stdout. It is guaranteed not to be a wrapper and may be a null string if no preprocessor can be made directly available. This preprocessor might be different from the one used by the C compiler. Don't forget to append cpplast after the preprocessor options.

"cppstdin"
From cppstdin.U:

This variable contains the command which will invoke the C preprocessor on standard input and put the output to stdout. It is primarily used by other Configure units that ask about preprocessor symbols.

"cppsymbols"
From Cppsym.U:

The variable contains the symbols defined by the C preprocessor alone. The symbols defined by cc or by cc when it calls cpp are not in this list, see ccsymbols and cppccsymbols. The list is a space-separated list of symbol=value tokens.

"crypt_r_proto"
From d_crypt_r.U:

This variable encodes the prototype of crypt_r. It is zero if d_crypt_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_crypt_r is defined.

"cryptlib"
From d_crypt.U:

This variable holds -lcrypt or the path to a libcrypt.a archive if the crypt() function is not defined in the standard C library. It is up to the Makefile to use this.

"csh"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the csh program. After Configure runs, the value is reset to a plain "csh" and is not useful.

"ctermid_r_proto"
From d_ctermid_r.U:

This variable encodes the prototype of ctermid_r. It is zero if d_ctermid_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_ctermid_r is defined.

"ctime_r_proto"
From d_ctime_r.U:

This variable encodes the prototype of ctime_r. It is zero if d_ctime_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_ctime_r is defined.

"d__fwalk"
From d__fwalk.U:

This variable conditionally defines "HAS__FWALK" if _fwalk() is available to apply a function to all the file handles.

"d_accept4"
From d_accept4.U:

This variable conditionally defines HAS_ACCEPT4 if accept4() is available to accept socket connections.

"d_access"
From d_access.U:

This variable conditionally defines "HAS_ACCESS" if the access() system call is available to check for access permissions using real IDs.

"d_accessx"
From d_accessx.U:

This variable conditionally defines the "HAS_ACCESSX" symbol, which indicates to the C program that the accessx() routine is available.

"d_acosh"
From d_acosh.U:

This variable conditionally defines the "HAS_ACOSH" symbol, which indicates to the C program that the acosh() routine is available.

"d_aintl"
From d_aintl.U:

This variable conditionally defines the "HAS_AINTL" symbol, which indicates to the C program that the aintl() routine is available. If copysignl is also present we can emulate modfl.

"d_alarm"
From d_alarm.U:

This variable conditionally defines the "HAS_ALARM" symbol, which indicates to the C program that the alarm() routine is available.

"d_archlib"
From archlib.U:

This variable conditionally defines "ARCHLIB" to hold the pathname of architecture-dependent library files for $package. If $archlib is the same as $privlib, then this is set to undef.

"d_asctime64"
From d_timefuncs64.U:

This variable conditionally defines the HAS_ASCTIME64 symbol, which indicates to the C program that the asctime64 () routine is available.

"d_asctime_r"
From d_asctime_r.U:

This variable conditionally defines the "HAS_ASCTIME_R" symbol, which indicates to the C program that the asctime_r() routine is available.

"d_asinh"
From d_asinh.U:

This variable conditionally defines the "HAS_ASINH" symbol, which indicates to the C program that the asinh() routine is available.

"d_atanh"
From d_atanh.U:

This variable conditionally defines the "HAS_ATANH" symbol, which indicates to the C program that the atanh() routine is available.

"d_atolf"
From atolf.U:

This variable conditionally defines the "HAS_ATOLF" symbol, which indicates to the C program that the atolf() routine is available.

"d_atoll"
From atoll.U:

This variable conditionally defines the "HAS_ATOLL" symbol, which indicates to the C program that the atoll() routine is available.

"d_attribute_always_inline"
From d_attribut.U:

This variable conditionally defines "HASATTRIBUTE_ALWAYS_INLINE", which indicates that the C compiler can know that certain functions should always be inlined.

"d_attribute_deprecated"
From d_attribut.U:

This variable conditionally defines "HASATTRIBUTE_DEPRECATED", which indicates that "GCC" can handle the attribute for marking deprecated APIs

"d_attribute_format"
From d_attribut.U:

This variable conditionally defines "HASATTRIBUTE_FORMAT", which indicates the C compiler can check for printf-like formats.

"d_attribute_malloc"
From d_attribut.U:

This variable conditionally defines "HASATTRIBUTE_MALLOC", which indicates the C compiler can understand functions as having malloc-like semantics.

"d_attribute_nonnull"
From d_attribut.U:

This variable conditionally defines "HASATTRIBUTE_NONNULL", which indicates that the C compiler can know that certain arguments must not be "NULL", and will check accordingly at compile time.

"d_attribute_noreturn"
From d_attribut.U:

This variable conditionally defines "HASATTRIBUTE_NORETURN", which indicates that the C compiler can know that certain functions are guaranteed never to return.

"d_attribute_pure"
From d_attribut.U:

This variable conditionally defines "HASATTRIBUTE_PURE", which indicates that the C compiler can know that certain functions are "pure" functions, meaning that they have no side effects, and only rely on function input and/or global data for their results.

"d_attribute_unused"
From d_attribut.U:

This variable conditionally defines "HASATTRIBUTE_UNUSED", which indicates that the C compiler can know that certain variables and arguments may not always be used, and to not throw warnings if they don't get used.

"d_attribute_warn_unused_result"
From d_attribut.U:

This variable conditionally defines "HASATTRIBUTE_WARN_UNUSED_RESULT", which indicates that the C compiler can know that certain functions have a return values that must not be ignored, such as malloc() or open().

"d_backtrace"
From d_backtrace.U:

This variable conditionally defines the "HAS_BACKTRACE" symbol, which indicates to the C program that the backtrace() routine is available to get a stack trace.

"d_bsd"
From Guess.U:

This symbol conditionally defines the symbol "BSD" when running on a "BSD" system.

"d_bsdgetpgrp"
From d_getpgrp.U:

This variable conditionally defines "USE_BSD_GETPGRP" if getpgrp needs one arguments whereas "USG" one needs none.

"d_bsdsetpgrp"
From d_setpgrp.U:

This variable conditionally defines "USE_BSD_SETPGRP" if setpgrp needs two arguments whereas "USG" one needs none. See also d_setpgid for a "POSIX" interface.

"d_builtin_add_overflow"
From d_builtin_overflow.U:

This variable conditionally defines "HAS_BUILTIN_ADD_OVERFLOW", which indicates that the compiler supports __builtin_add_overflow(x,y,&z) for safely adding x and y into z while checking for overflow.

"d_builtin_choose_expr"
From d_builtin.U:

This conditionally defines "HAS_BUILTIN_CHOOSE_EXPR", which indicates that the compiler supports __builtin_choose_expr(x,y,z). This built-in function is analogous to the "x?y:z" operator in C, except that the expression returned has its type unaltered by promotion rules. Also, the built-in function does not evaluate the expression that was not chosen.

"d_builtin_expect"
From d_builtin.U:

This conditionally defines "HAS_BUILTIN_EXPECT", which indicates that the compiler supports __builtin_expect(exp,c). You may use __builtin_expect to provide the compiler with branch prediction information.

"d_builtin_mul_overflow"
From d_builtin_overflow.U:

This variable conditionally defines "HAS_BUILTIN_MUL_OVERFLOW", which indicates that the compiler supports __builtin_mul_overflow(x,y,&z) for safely multiplying x and y into z while checking for overflow.

"d_builtin_sub_overflow"
From d_builtin_overflow.U:

This variable conditionally defines "HAS_BUILTIN_SUB_OVERFLOW", which indicates that the compiler supports __builtin_sub_overflow(x,y,&z) for safely subtracting y from x into z while checking for overflow.

"d_c99_variadic_macros"
From d_c99_variadic.U:

This variable conditionally defines the HAS_C99_VARIADIC_MACROS symbol, which indicates to the C program that C99 variadic macros are available.

"d_casti32"
From d_casti32.U:

This variable conditionally defines CASTI32, which indicates whether the C compiler can cast large floats to 32-bit ints.

"d_castneg"
From d_castneg.U:

This variable conditionally defines "CASTNEG", which indicates whether the C compiler can cast negative float to unsigned.

"d_cbrt"
From d_cbrt.U:

This variable conditionally defines the "HAS_CBRT" symbol, which indicates to the C program that the cbrt() (cube root) function is available.

"d_chown"
From d_chown.U:

This variable conditionally defines the "HAS_CHOWN" symbol, which indicates to the C program that the chown() routine is available.

"d_chroot"
From d_chroot.U:

This variable conditionally defines the "HAS_CHROOT" symbol, which indicates to the C program that the chroot() routine is available.

"d_chsize"
From d_chsize.U:

This variable conditionally defines the "CHSIZE" symbol, which indicates to the C program that the chsize() routine is available to truncate files. You might need a -lx to get this routine.

"d_class"
From d_class.U:

This variable conditionally defines the "HAS_CLASS" symbol, which indicates to the C program that the class() routine is available.

"d_clearenv"
From d_clearenv.U:

This variable conditionally defines the "HAS_CLEARENV" symbol, which indicates to the C program that the clearenv () routine is available.

"d_closedir"
From d_closedir.U:

This variable conditionally defines "HAS_CLOSEDIR" if closedir() is available.

"d_cmsghdr_s"
From d_cmsghdr_s.U:

This variable conditionally defines the "HAS_STRUCT_CMSGHDR" symbol, which indicates that the struct cmsghdr is supported.

"d_copysign"
From d_copysign.U:

This variable conditionally defines the "HAS_COPYSIGN" symbol, which indicates to the C program that the copysign() routine is available.

"d_copysignl"
From d_copysignl.U:

This variable conditionally defines the "HAS_COPYSIGNL" symbol, which indicates to the C program that the copysignl() routine is available. If aintl is also present we can emulate modfl.

"d_cplusplus"
From d_cplusplus.U:

This variable conditionally defines the "USE_CPLUSPLUS" symbol, which indicates that a C++ compiler was used to compiled Perl and will be used to compile extensions.

"d_crypt"
From d_crypt.U:

This variable conditionally defines the "CRYPT" symbol, which indicates to the C program that the crypt() routine is available to encrypt passwords and the like.

"d_crypt_r"
From d_crypt_r.U:

This variable conditionally defines the "HAS_CRYPT_R" symbol, which indicates to the C program that the crypt_r() routine is available.

"d_csh"
From d_csh.U:

This variable conditionally defines the "CSH" symbol, which indicates to the C program that the C-shell exists.

"d_ctermid"
From d_ctermid.U:

This variable conditionally defines "CTERMID" if ctermid() is available to generate filename for terminal.

"d_ctermid_r"
From d_ctermid_r.U:

This variable conditionally defines the "HAS_CTERMID_R" symbol, which indicates to the C program that the ctermid_r() routine is available.

"d_ctime64"
From d_timefuncs64.U:

This variable conditionally defines the HAS_CTIME64 symbol, which indicates to the C program that the ctime64 () routine is available.

"d_ctime_r"
From d_ctime_r.U:

This variable conditionally defines the "HAS_CTIME_R" symbol, which indicates to the C program that the ctime_r() routine is available.

"d_cuserid"
From d_cuserid.U:

This variable conditionally defines the "HAS_CUSERID" symbol, which indicates to the C program that the cuserid() routine is available to get character login names.

"d_dbminitproto"
From d_dbminitproto.U:

This variable conditionally defines the "HAS_DBMINIT_PROTO" symbol, which indicates to the C program that the system provides a prototype for the dbminit() function. Otherwise, it is up to the program to supply one.

"d_difftime"
From d_difftime.U:

This variable conditionally defines the "HAS_DIFFTIME" symbol, which indicates to the C program that the difftime() routine is available.

"d_difftime64"
From d_timefuncs64.U:

This variable conditionally defines the HAS_DIFFTIME64 symbol, which indicates to the C program that the difftime64 () routine is available.

"d_dir_dd_fd"
From d_dir_dd_fd.U:

This variable conditionally defines the "HAS_DIR_DD_FD" symbol, which indicates that the "DIR" directory stream type contains a member variable called dd_fd.

"d_dirfd"
From d_dirfd.U:

This variable conditionally defines the "HAS_DIRFD" constant, which indicates to the C program that dirfd() is available to return the file descriptor of a directory stream.

"d_dirnamlen"
From i_dirent.U:

This variable conditionally defines "DIRNAMLEN", which indicates to the C program that the length of directory entry names is provided by a d_namelen field.

"d_dladdr"
From d_dladdr.U:

This variable conditionally defines the "HAS_DLADDR" symbol, which indicates to the C program that the dladdr() routine is available to get a stack trace.

"d_dlerror"
From d_dlerror.U:

This variable conditionally defines the "HAS_DLERROR" symbol, which indicates to the C program that the dlerror() routine is available.

"d_dlopen"
From d_dlopen.U:

This variable conditionally defines the "HAS_DLOPEN" symbol, which indicates to the C program that the dlopen() routine is available.

"d_dlsymun"
From d_dlsymun.U:

This variable conditionally defines "DLSYM_NEEDS_UNDERSCORE", which indicates that we need to prepend an underscore to the symbol name before calling dlsym().

"d_dosuid"
From d_dosuid.U:

This variable conditionally defines the symbol "DOSUID", which tells the C program that it should insert setuid emulation code on hosts which have setuid #! scripts disabled.

"d_double_has_inf"
From longdblfio.U:

This variable conditionally defines the symbol "DOUBLE_HAS_INF" which indicates that the double type has an infinity.

"d_double_has_nan"
From longdblfio.U:

This variable conditionally defines the symbol "DOUBLE_HAS_NAN" which indicates that the double type has a not-a-number.

"d_double_has_negative_zero"
From longdblfio.U:

This variable conditionally defines the symbol "DOUBLE_HAS_NEGATIVE_ZERO" which indicates that the double type has a negative zero.

"d_double_has_subnormals"
From longdblfio.U:

This variable conditionally defines the symbol "DOUBLE_HAS_SUBNORMALS" which indicates that the double type has subnormals (denormals).

"d_double_style_cray"
From longdblfio.U:

This variable conditionally defines the symbol "DOUBLE_STYLE_CRAY" which indicates that the double is the 64-bit "CRAY" mainframe format.

"d_double_style_ibm"
From longdblfio.U:

This variable conditionally defines the symbol "DOUBLE_STYLE_IBM", which indicates that the double is the 64-bit "IBM" mainframe format.

"d_double_style_ieee"
From longdblfio.U:

This variable conditionally defines the symbol "DOUBLE_STYLE_IEEE", which indicates that the double is the 64-bit "IEEE" 754.

"d_double_style_vax"
From longdblfio.U:

This variable conditionally defines the symbol "DOUBLE_STYLE_VAX", which indicates that the double is the 64-bit "VAX" format D or G.

"d_drand48_r"
From d_drand48_r.U:

This variable conditionally defines the HAS_DRAND48_R symbol, which indicates to the C program that the drand48_r() routine is available.

"d_drand48proto"
From d_drand48proto.U:

This variable conditionally defines the HAS_DRAND48_PROTO symbol, which indicates to the C program that the system provides a prototype for the drand48() function. Otherwise, it is up to the program to supply one.

"d_dup2"
From d_dup2.U:

This variable conditionally defines HAS_DUP2 if dup2() is available to duplicate file descriptors.

"d_dup3"
From d_dup3.U:

This variable conditionally defines HAS_DUP3 if dup3() is available to duplicate file descriptors.

"d_duplocale"
From d_newlocale.U:

This variable conditionally defines the "HAS_DUPLOCALE" symbol, which indicates to the C program that the duplocale() routine is available to duplicate a locale object.

"d_eaccess"
From d_eaccess.U:

This variable conditionally defines the "HAS_EACCESS" symbol, which indicates to the C program that the eaccess() routine is available.

"d_endgrent"
From d_endgrent.U:

This variable conditionally defines the "HAS_ENDGRENT" symbol, which indicates to the C program that the endgrent() routine is available for sequential access of the group database.

"d_endgrent_r"
From d_endgrent_r.U:

This variable conditionally defines the "HAS_ENDGRENT_R" symbol, which indicates to the C program that the endgrent_r() routine is available.

"d_endhent"
From d_endhent.U:

This variable conditionally defines "HAS_ENDHOSTENT" if endhostent() is available to close whatever was being used for host queries.

"d_endhostent_r"
From d_endhostent_r.U:

This variable conditionally defines the "HAS_ENDHOSTENT_R" symbol, which indicates to the C program that the endhostent_r() routine is available.

"d_endnent"
From d_endnent.U:

This variable conditionally defines "HAS_ENDNETENT" if endnetent() is available to close whatever was being used for network queries.

"d_endnetent_r"
From d_endnetent_r.U:

This variable conditionally defines the "HAS_ENDNETENT_R" symbol, which indicates to the C program that the endnetent_r() routine is available.

"d_endpent"
From d_endpent.U:

This variable conditionally defines "HAS_ENDPROTOENT" if endprotoent() is available to close whatever was being used for protocol queries.

"d_endprotoent_r"
From d_endprotoent_r.U:

This variable conditionally defines the "HAS_ENDPROTOENT_R" symbol, which indicates to the C program that the endprotoent_r() routine is available.

"d_endpwent"
From d_endpwent.U:

This variable conditionally defines the "HAS_ENDPWENT" symbol, which indicates to the C program that the endpwent() routine is available for sequential access of the passwd database.

"d_endpwent_r"
From d_endpwent_r.U:

This variable conditionally defines the "HAS_ENDPWENT_R" symbol, which indicates to the C program that the endpwent_r() routine is available.

"d_endsent"
From d_endsent.U:

This variable conditionally defines "HAS_ENDSERVENT" if endservent() is available to close whatever was being used for service queries.

"d_endservent_r"
From d_endservent_r.U:

This variable conditionally defines the "HAS_ENDSERVENT_R" symbol, which indicates to the C program that the endservent_r() routine is available.

"d_eofnblk"
From nblock_io.U:

This variable conditionally defines "EOF_NONBLOCK" if "EOF" can be seen when reading from a non-blocking I/O source.

"d_erf"
From d_erf.U:

This variable conditionally defines the "HAS_ERF" symbol, which indicates to the C program that the erf() routine is available.

"d_erfc"
From d_erfc.U:

This variable conditionally defines the "HAS_ERFC" symbol, which indicates to the C program that the erfc() routine is available.

"d_eunice"
From Guess.U:

This variable conditionally defines the symbols "EUNICE" and "VAX", which alerts the C program that it must deal with idiosyncrasies of "VMS".

"d_exp2"
From d_exp2.U:

This variable conditionally defines the HAS_EXP2 symbol, which indicates to the C program that the exp2() routine is available.

"d_expm1"
From d_expm1.U:

This variable conditionally defines the HAS_EXPM1 symbol, which indicates to the C program that the expm1() routine is available.

"d_faststdio"
From d_faststdio.U:

This variable conditionally defines the "HAS_FAST_STDIO" symbol, which indicates to the C program that the "fast stdio" is available to manipulate the stdio buffers directly.

"d_fchdir"
From d_fchdir.U:

This variable conditionally defines the "HAS_FCHDIR" symbol, which indicates to the C program that the fchdir() routine is available.

"d_fchmod"
From d_fchmod.U:

This variable conditionally defines the "HAS_FCHMOD" symbol, which indicates to the C program that the fchmod() routine is available to change mode of opened files.

"d_fchmodat"
From d_fsat.U:

This variable conditionally defines the "HAS_FCHMODAT" symbol, which indicates the "POSIX" fchmodat() function is available.

"d_fchown"
From d_fchown.U:

This variable conditionally defines the "HAS_FCHOWN" symbol, which indicates to the C program that the fchown() routine is available to change ownership of opened files.

"d_fcntl"
From d_fcntl.U:

This variable conditionally defines the "HAS_FCNTL" symbol, and indicates whether the fcntl() function exists

"d_fcntl_can_lock"
From d_fcntl_can_lock.U:

This variable conditionally defines the "FCNTL_CAN_LOCK" symbol and indicates whether file locking with fcntl() works.

"d_fd_macros"
From d_fd_set.U:

This variable contains the eventual value of the "HAS_FD_MACROS" symbol, which indicates if your C compiler knows about the macros which manipulate an fd_set.

"d_fd_set"
From d_fd_set.U:

This variable contains the eventual value of the "HAS_FD_SET" symbol, which indicates if your C compiler knows about the fd_set typedef.

"d_fdclose"
From d_fdclose.U:

This variable conditionally defines the "HAS_FDCLOSE" symbol, which indicates to the C program that the fdclose() routine is available.

"d_fdim"
From d_fdim.U:

This variable conditionally defines the "HAS_FDIM" symbol, which indicates to the C program that the fdim() routine is available.

"d_fds_bits"
From d_fd_set.U:

This variable contains the eventual value of the "HAS_FDS_BITS" symbol, which indicates if your fd_set typedef contains the fds_bits member. If you have an fd_set typedef, but the dweebs who installed it did a half-fast job and neglected to provide the macros to manipulate an fd_set, "HAS_FDS_BITS" will let us know how to fix the gaffe.

"d_fegetround"
From d_fegetround.U:

This variable conditionally defines "HAS_FEGETROUND" if fegetround() is available to get the floating point rounding mode.

"d_fgetpos"
From d_fgetpos.U:

This variable conditionally defines "HAS_FGETPOS" if fgetpos() is available to get the file position indicator.

"d_finite"
From d_finite.U:

This variable conditionally defines the "HAS_FINITE" symbol, which indicates to the C program that the finite() routine is available.

"d_finitel"
From d_finitel.U:

This variable conditionally defines the "HAS_FINITEL" symbol, which indicates to the C program that the finitel() routine is available.

"d_flexfnam"
From d_flexfnam.U:

This variable conditionally defines the "FLEXFILENAMES" symbol, which indicates that the system supports filenames longer than 14 characters.

"d_flock"
From d_flock.U:

This variable conditionally defines "HAS_FLOCK" if flock() is available to do file locking.

"d_flockproto"
From d_flockproto.U:

This variable conditionally defines the "HAS_FLOCK_PROTO" symbol, which indicates to the C program that the system provides a prototype for the flock() function. Otherwise, it is up to the program to supply one.

"d_fma"
From d_fma.U:

This variable conditionally defines the "HAS_FMA" symbol, which indicates to the C program that the fma() routine is available.

"d_fmax"
From d_fmax.U:

This variable conditionally defines the "HAS_FMAX" symbol, which indicates to the C program that the fmax() routine is available.

"d_fmin"
From d_fmin.U:

This variable conditionally defines the "HAS_FMIN" symbol, which indicates to the C program that the fmin() routine is available.

"d_fork"
From d_fork.U:

This variable conditionally defines the "HAS_FORK" symbol, which indicates to the C program that the fork() routine is available.

"d_fp_class"
From d_fp_class.U:

This variable conditionally defines the "HAS_FP_CLASS" symbol, which indicates to the C program that the fp_class() routine is available.

"d_fp_classify"
From d_fpclassify.U:

This variable conditionally defines the "HAS_FP_CLASSIFY" symbol, which indicates to the C program that the fp_classify() routine is available.

"d_fp_classl"
From d_fp_classl.U:

This variable conditionally defines the "HAS_FP_CLASSL" symbol, which indicates to the C program that the fp_classl() routine is available.

"d_fpathconf"
From d_pathconf.U:

This variable conditionally defines the "HAS_FPATHCONF" symbol, which indicates to the C program that the pathconf() routine is available to determine file-system related limits and options associated with a given open file descriptor.

"d_fpclass"
From d_fpclass.U:

This variable conditionally defines the "HAS_FPCLASS" symbol, which indicates to the C program that the fpclass() routine is available.

"d_fpclassify"
From d_fpclassify.U:

This variable conditionally defines the "HAS_FPCLASSIFY" symbol, which indicates to the C program that the fpclassify() routine is available.

"d_fpclassl"
From d_fpclassl.U:

This variable conditionally defines the "HAS_FPCLASSL" symbol, which indicates to the C program that the fpclassl() routine is available.

"d_fpgetround"
From d_fpgetround.U:

This variable conditionally defines "HAS_FPGETROUND" if fpgetround() is available to get the floating point rounding mode.

"d_fpos64_t"
From d_fpos64_t.U:

This symbol will be defined if the C compiler supports fpos64_t.

"d_freelocale"
From d_newlocale.U:

This variable conditionally defines the "HAS_FREELOCALE" symbol, which indicates to the C program that the freelocale() routine is available to deallocates the resources associated with a locale object.

"d_frexpl"
From d_frexpl.U:

This variable conditionally defines the "HAS_FREXPL" symbol, which indicates to the C program that the frexpl() routine is available.

"d_fs_data_s"
From d_fs_data_s.U:

This variable conditionally defines the "HAS_STRUCT_FS_DATA" symbol, which indicates that the struct fs_data is supported.

"d_fseeko"
From d_fseeko.U:

This variable conditionally defines the "HAS_FSEEKO" symbol, which indicates to the C program that the fseeko() routine is available.

"d_fsetpos"
From d_fsetpos.U:

This variable conditionally defines "HAS_FSETPOS" if fsetpos() is available to set the file position indicator.

"d_fstatfs"
From d_fstatfs.U:

This variable conditionally defines the "HAS_FSTATFS" symbol, which indicates to the C program that the fstatfs() routine is available.

"d_fstatvfs"
From d_statvfs.U:

This variable conditionally defines the "HAS_FSTATVFS" symbol, which indicates to the C program that the fstatvfs() routine is available.

"d_fsync"
From d_fsync.U:

This variable conditionally defines the "HAS_FSYNC" symbol, which indicates to the C program that the fsync() routine is available.

"d_ftello"
From d_ftello.U:

This variable conditionally defines the "HAS_FTELLO" symbol, which indicates to the C program that the ftello() routine is available.

"d_ftime"
From d_ftime.U:

This variable conditionally defines the "HAS_FTIME" symbol, which indicates that the ftime() routine exists. The ftime() routine is basically a sub-second accuracy clock.

"d_futimes"
From d_futimes.U:

This variable conditionally defines the "HAS_FUTIMES" symbol, which indicates to the C program that the futimes() routine is available.

"d_gai_strerror"
From d_gai_strerror.U:

This variable conditionally defines the "HAS_GAI_STRERROR" symbol if the gai_strerror() routine is available and can be used to translate error codes returned by getaddrinfo() into human readable strings.

"d_Gconvert"
From d_gconvert.U:

This variable holds what Gconvert is defined as to convert floating point numbers into strings. By default, Configure sets "this" macro to use the first of gconvert, gcvt, or sprintf that pass sprintf-%g-like behavior tests. If perl is using long doubles, the macro uses the first of the following functions that pass Configure's tests: qgcvt, sprintf (if Configure knows how to make sprintf format long doubles--see sPRIgldbl), gconvert, gcvt, and sprintf (casting to double). The gconvert_preference and gconvert_ld_preference variables can be used to alter Configure's preferences, for doubles and long doubles, respectively. If present, they contain a space-separated list of one or more of the above function names in the order they should be tried.

d_Gconvert may be set to override Configure with a platform- specific function. If this function expects a double, a different value may need to be set by the uselongdouble.cbu call-back unit so that long doubles can be formatted without loss of precision.

"d_gdbm_ndbm_h_uses_prototypes"
From i_ndbm.U:

This variable conditionally defines the "NDBM_H_USES_PROTOTYPES" symbol, which indicates that the gdbm-ndbm.h include file uses real "ANSI" C prototypes instead of K&R style function declarations. K&R style declarations are unsupported in C++, so the include file requires special handling when using a C++ compiler and this variable is undefined. Consult the different d_*ndbm_h_uses_prototypes variables to get the same information for alternative ndbm.h include files.

"d_gdbmndbm_h_uses_prototypes"
From i_ndbm.U:

This variable conditionally defines the "NDBM_H_USES_PROTOTYPES" symbol, which indicates that the gdbm/ndbm.h include file uses real "ANSI" C prototypes instead of K&R style function declarations. K&R style declarations are unsupported in C++, so the include file requires special handling when using a C++ compiler and this variable is undefined. Consult the different d_*ndbm_h_uses_prototypes variables to get the same information for alternative ndbm.h include files.

"d_getaddrinfo"
From d_getaddrinfo.U:

This variable conditionally defines the "HAS_GETADDRINFO" symbol, which indicates to the C program that the getaddrinfo() function is available.

"d_getcwd"
From d_getcwd.U:

This variable conditionally defines the "HAS_GETCWD" symbol, which indicates to the C program that the getcwd() routine is available to get the current working directory.

"d_getenv_preserves_other_thread"
From d_getenv_thread.U:

This variable conditionally defines the "GETENV_PRESERVES_OTHER_THREAD" symbol, which indicates to the C program that the getenv() system call does not zap the static buffer in a different thread.

"d_getespwnam"
From d_getespwnam.U:

This variable conditionally defines "HAS_GETESPWNAM" if getespwnam() is available to retrieve enhanced (shadow) password entries by name.

"d_getfsstat"
From d_getfsstat.U:

This variable conditionally defines the "HAS_GETFSSTAT" symbol, which indicates to the C program that the getfsstat() routine is available.

"d_getgrent"
From d_getgrent.U:

This variable conditionally defines the "HAS_GETGRENT" symbol, which indicates to the C program that the getgrent() routine is available for sequential access of the group database.

"d_getgrent_r"
From d_getgrent_r.U:

This variable conditionally defines the "HAS_GETGRENT_R" symbol, which indicates to the C program that the getgrent_r() routine is available.

"d_getgrgid_r"
From d_getgrgid_r.U:

This variable conditionally defines the "HAS_GETGRGID_R" symbol, which indicates to the C program that the getgrgid_r() routine is available.

"d_getgrnam_r"
From d_getgrnam_r.U:

This variable conditionally defines the "HAS_GETGRNAM_R" symbol, which indicates to the C program that the getgrnam_r() routine is available.

"d_getgrps"
From d_getgrps.U:

This variable conditionally defines the "HAS_GETGROUPS" symbol, which indicates to the C program that the getgroups() routine is available to get the list of process groups.

"d_gethbyaddr"
From d_gethbyad.U:

This variable conditionally defines the "HAS_GETHOSTBYADDR" symbol, which indicates to the C program that the gethostbyaddr() routine is available to look up hosts by their "IP" addresses.

"d_gethbyname"
From d_gethbynm.U:

This variable conditionally defines the "HAS_GETHOSTBYNAME" symbol, which indicates to the C program that the gethostbyname() routine is available to look up host names in some data base or other.

"d_gethent"
From d_gethent.U:

This variable conditionally defines "HAS_GETHOSTENT" if gethostent() is available to look up host names in some data base or another.

"d_gethname"
From d_gethname.U:

This variable conditionally defines the "HAS_GETHOSTNAME" symbol, which indicates to the C program that the gethostname() routine may be used to derive the host name.

"d_gethostbyaddr_r"
From d_gethostbyaddr_r.U:

This variable conditionally defines the "HAS_GETHOSTBYADDR_R" symbol, which indicates to the C program that the gethostbyaddr_r() routine is available.

"d_gethostbyname_r"
From d_gethostbyname_r.U:

This variable conditionally defines the "HAS_GETHOSTBYNAME_R" symbol, which indicates to the C program that the gethostbyname_r() routine is available.

"d_gethostent_r"
From d_gethostent_r.U:

This variable conditionally defines the "HAS_GETHOSTENT_R" symbol, which indicates to the C program that the gethostent_r() routine is available.

"d_gethostprotos"
From d_gethostprotos.U:

This variable conditionally defines the "HAS_GETHOST_PROTOS" symbol, which indicates to the C program that <netdb.h> supplies prototypes for the various gethost*() functions. See also netdbtype.U for probing for various netdb types.

"d_getitimer"
From d_getitimer.U:

This variable conditionally defines the "HAS_GETITIMER" symbol, which indicates to the C program that the getitimer() routine is available.

"d_getlogin"
From d_getlogin.U:

This variable conditionally defines the "HAS_GETLOGIN" symbol, which indicates to the C program that the getlogin() routine is available to get the login name.

"d_getlogin_r"
From d_getlogin_r.U:

This variable conditionally defines the "HAS_GETLOGIN_R" symbol, which indicates to the C program that the getlogin_r() routine is available.

"d_getmnt"
From d_getmnt.U:

This variable conditionally defines the "HAS_GETMNT" symbol, which indicates to the C program that the getmnt() routine is available to retrieve one or more mount info blocks by filename.

"d_getmntent"
From d_getmntent.U:

This variable conditionally defines the "HAS_GETMNTENT" symbol, which indicates to the C program that the getmntent() routine is available to iterate through mounted files to get their mount info.

"d_getnameinfo"
From d_getnameinfo.U:

This variable conditionally defines the "HAS_GETNAMEINFO" symbol, which indicates to the C program that the getnameinfo() function is available.

"d_getnbyaddr"
From d_getnbyad.U:

This variable conditionally defines the "HAS_GETNETBYADDR" symbol, which indicates to the C program that the getnetbyaddr() routine is available to look up networks by their "IP" addresses.

"d_getnbyname"
From d_getnbynm.U:

This variable conditionally defines the "HAS_GETNETBYNAME" symbol, which indicates to the C program that the getnetbyname() routine is available to look up networks by their names.

"d_getnent"
From d_getnent.U:

This variable conditionally defines "HAS_GETNETENT" if getnetent() is available to look up network names in some data base or another.

"d_getnetbyaddr_r"
From d_getnetbyaddr_r.U:

This variable conditionally defines the "HAS_GETNETBYADDR_R" symbol, which indicates to the C program that the getnetbyaddr_r() routine is available.

"d_getnetbyname_r"
From d_getnetbyname_r.U:

This variable conditionally defines the "HAS_GETNETBYNAME_R" symbol, which indicates to the C program that the getnetbyname_r() routine is available.

"d_getnetent_r"
From d_getnetent_r.U:

This variable conditionally defines the "HAS_GETNETENT_R" symbol, which indicates to the C program that the getnetent_r() routine is available.

"d_getnetprotos"
From d_getnetprotos.U:

This variable conditionally defines the "HAS_GETNET_PROTOS" symbol, which indicates to the C program that <netdb.h> supplies prototypes for the various getnet*() functions. See also netdbtype.U for probing for various netdb types.

"d_getpagsz"
From d_getpagsz.U:

This variable conditionally defines "HAS_GETPAGESIZE" if getpagesize() is available to get the system page size.

"d_getpbyname"
From d_getprotby.U:

This variable conditionally defines the "HAS_GETPROTOBYNAME" symbol, which indicates to the C program that the getprotobyname() routine is available to look up protocols by their name.

"d_getpbynumber"
From d_getprotby.U:

This variable conditionally defines the "HAS_GETPROTOBYNUMBER" symbol, which indicates to the C program that the getprotobynumber() routine is available to look up protocols by their number.

"d_getpent"
From d_getpent.U:

This variable conditionally defines "HAS_GETPROTOENT" if getprotoent() is available to look up protocols in some data base or another.

"d_getpgid"
From d_getpgid.U:

This variable conditionally defines the "HAS_GETPGID" symbol, which indicates to the C program that the getpgid(pid) function is available to get the process group id.

"d_getpgrp"
From d_getpgrp.U:

This variable conditionally defines "HAS_GETPGRP" if getpgrp() is available to get the current process group.

"d_getpgrp2"
From d_getpgrp2.U:

This variable conditionally defines the HAS_GETPGRP2 symbol, which indicates to the C program that the getpgrp2() (as in DG/"UX") routine is available to get the current process group.

"d_getppid"
From d_getppid.U:

This variable conditionally defines the "HAS_GETPPID" symbol, which indicates to the C program that the getppid() routine is available to get the parent process "ID".

"d_getprior"
From d_getprior.U:

This variable conditionally defines "HAS_GETPRIORITY" if getpriority() is available to get a process's priority.

"d_getprotobyname_r"
From d_getprotobyname_r.U:

This variable conditionally defines the "HAS_GETPROTOBYNAME_R" symbol, which indicates to the C program that the getprotobyname_r() routine is available.

"d_getprotobynumber_r"
From d_getprotobynumber_r.U:

This variable conditionally defines the "HAS_GETPROTOBYNUMBER_R" symbol, which indicates to the C program that the getprotobynumber_r() routine is available.

"d_getprotoent_r"
From d_getprotoent_r.U:

This variable conditionally defines the "HAS_GETPROTOENT_R" symbol, which indicates to the C program that the getprotoent_r() routine is available.

"d_getprotoprotos"
From d_getprotoprotos.U:

This variable conditionally defines the "HAS_GETPROTO_PROTOS" symbol, which indicates to the C program that <netdb.h> supplies prototypes for the various getproto*() functions. See also netdbtype.U for probing for various netdb types.

"d_getprpwnam"
From d_getprpwnam.U:

This variable conditionally defines "HAS_GETPRPWNAM" if getprpwnam() is available to retrieve protected (shadow) password entries by name.

"d_getpwent"
From d_getpwent.U:

This variable conditionally defines the "HAS_GETPWENT" symbol, which indicates to the C program that the getpwent() routine is available for sequential access of the passwd database.

"d_getpwent_r"
From d_getpwent_r.U:

This variable conditionally defines the "HAS_GETPWENT_R" symbol, which indicates to the C program that the getpwent_r() routine is available.

"d_getpwnam_r"
From d_getpwnam_r.U:

This variable conditionally defines the "HAS_GETPWNAM_R" symbol, which indicates to the C program that the getpwnam_r() routine is available.

"d_getpwuid_r"
From d_getpwuid_r.U:

This variable conditionally defines the "HAS_GETPWUID_R" symbol, which indicates to the C program that the getpwuid_r() routine is available.

"d_getsbyname"
From d_getsrvby.U:

This variable conditionally defines the "HAS_GETSERVBYNAME" symbol, which indicates to the C program that the getservbyname() routine is available to look up services by their name.

"d_getsbyport"
From d_getsrvby.U:

This variable conditionally defines the "HAS_GETSERVBYPORT" symbol, which indicates to the C program that the getservbyport() routine is available to look up services by their port.

"d_getsent"
From d_getsent.U:

This variable conditionally defines "HAS_GETSERVENT" if getservent() is available to look up network services in some data base or another.

"d_getservbyname_r"
From d_getservbyname_r.U:

This variable conditionally defines the "HAS_GETSERVBYNAME_R" symbol, which indicates to the C program that the getservbyname_r() routine is available.

"d_getservbyport_r"
From d_getservbyport_r.U:

This variable conditionally defines the "HAS_GETSERVBYPORT_R" symbol, which indicates to the C program that the getservbyport_r() routine is available.

"d_getservent_r"
From d_getservent_r.U:

This variable conditionally defines the "HAS_GETSERVENT_R" symbol, which indicates to the C program that the getservent_r() routine is available.

"d_getservprotos"
From d_getservprotos.U:

This variable conditionally defines the "HAS_GETSERV_PROTOS" symbol, which indicates to the C program that <netdb.h> supplies prototypes for the various getserv*() functions. See also netdbtype.U for probing for various netdb types.

"d_getspnam"
From d_getspnam.U:

This variable conditionally defines "HAS_GETSPNAM" if getspnam() is available to retrieve SysV shadow password entries by name.

"d_getspnam_r"
From d_getspnam_r.U:

This variable conditionally defines the "HAS_GETSPNAM_R" symbol, which indicates to the C program that the getspnam_r() routine is available.

"d_gettimeod"
From d_ftime.U:

This variable conditionally defines the "HAS_GETTIMEOFDAY" symbol, which indicates that the gettimeofday() system call exists (to obtain a sub-second accuracy clock). You should probably include <sys/resource.h>.

"d_gmtime64"
From d_timefuncs64.U:

This variable conditionally defines the HAS_GMTIME64 symbol, which indicates to the C program that the gmtime64 () routine is available.

"d_gmtime_r"
From d_gmtime_r.U:

This variable conditionally defines the "HAS_GMTIME_R" symbol, which indicates to the C program that the gmtime_r() routine is available.

"d_gnulibc"
From d_gnulibc.U:

Defined if we're dealing with the "GNU" C Library.

"d_grpasswd"
From i_grp.U:

This variable conditionally defines "GRPASSWD", which indicates that struct group in <grp.h> contains gr_passwd.

"d_has_C_UTF8"
From d_setlocale.U:

This variable is set to either "true" or "false" depending on whether the compilation system supports the C.UTF-8 locale.

"d_hasmntopt"
From d_hasmntopt.U:

This variable conditionally defines the "HAS_HASMNTOPT" symbol, which indicates to the C program that the hasmntopt() routine is available to query the mount options of file systems.

"d_htonl"
From d_htonl.U:

This variable conditionally defines "HAS_HTONL" if htonl() and its friends are available to do network order byte swapping.

"d_hypot"
From d_hypot.U:

This variable conditionally defines "HAS_HYPOT" if hypot is available for numerically stable hypotenuse function.

"d_ilogb"
From d_ilogb.U:

This variable conditionally defines the "HAS_ILOGB" symbol, which indicates to the C program that the ilogb() routine is available for extracting the exponent of double x as a signed integer.

"d_ilogbl"
From d_ilogbl.U:

This variable conditionally defines the "HAS_ILOGBL" symbol, which indicates to the C program that the ilogbl() routine is available for extracting the exponent of long double x as a signed integer. If scalbnl is also present we can emulate frexpl.

"d_inc_version_list"
From inc_version_list.U:

This variable conditionally defines "PERL_INC_VERSION_LIST". It is set to undef when "PERL_INC_VERSION_LIST" is empty.

"d_inetaton"
From d_inetaton.U:

This variable conditionally defines the "HAS_INET_ATON" symbol, which indicates to the C program that the inet_aton() function is available to parse "IP" address "dotted-quad" strings.

"d_inetntop"
From d_inetntop.U:

This variable conditionally defines the "HAS_INETNTOP" symbol, which indicates to the C program that the inet_ntop() function is available.

"d_inetpton"
From d_inetpton.U:

This variable conditionally defines the "HAS_INETPTON" symbol, which indicates to the C program that the inet_pton() function is available.

"d_int64_t"
From d_int64_t.U:

This symbol will be defined if the C compiler supports int64_t.

"d_ip_mreq"
From d_socket.U:

This variable conditionally defines the "HAS_IP_MREQ" symbol, which indicates the availability of a struct ip_mreq.

"d_ip_mreq_source"
From d_socket.U:

This variable conditionally defines the "HAS_IP_MREQ_SOURCE" symbol, which indicates the availability of a struct ip_mreq_source.

"d_ipv6_mreq"
From d_socket.U:

This variable conditionally defines the HAS_IPV6_MREQ symbol, which indicates the availability of a struct ipv6_mreq.

"d_ipv6_mreq_source"
From d_socket.U:

This variable conditionally defines the HAS_IPV6_MREQ_SOURCE symbol, which indicates the availability of a struct ipv6_mreq_source.

"d_isascii"
From d_isascii.U:

This variable conditionally defines the "HAS_ISASCII" constant, which indicates to the C program that isascii() is available.

"d_isblank"
From d_isblank.U:

This variable conditionally defines the "HAS_ISBLANK" constant, which indicates to the C program that isblank() is available.

"d_isfinite"
From d_isfinite.U:

This variable conditionally defines the "HAS_ISFINITE" symbol, which indicates to the C program that the isfinite() routine is available.

"d_isfinitel"
From d_isfinitel.U:

This variable conditionally defines the "HAS_ISFINITEL" symbol, which indicates to the C program that the isfinitel() routine is available.

"d_isinf"
From d_isinf.U:

This variable conditionally defines the "HAS_ISINF" symbol, which indicates to the C program that the isinf() routine is available.

"d_isinfl"
From d_isinfl.U:

This variable conditionally defines the "HAS_ISINFL" symbol, which indicates to the C program that the isinfl() routine is available.

"d_isless"
From d_isless.U:

This variable conditionally defines the "HAS_ISLESS" symbol, which indicates to the C program that the isless() routine is available.

"d_isnan"
From d_isnan.U:

This variable conditionally defines the "HAS_ISNAN" symbol, which indicates to the C program that the isnan() routine is available.

"d_isnanl"
From d_isnanl.U:

This variable conditionally defines the "HAS_ISNANL" symbol, which indicates to the C program that the isnanl() routine is available.

"d_isnormal"
From d_isnormal.U:

This variable conditionally defines the "HAS_ISNORMAL" symbol, which indicates to the C program that the isnormal() routine is available.

"d_j0"
From d_j0.U:

This variable conditionally defines the HAS_J0 symbol, which indicates to the C program that the j0() routine is available.

"d_j0l"
From d_j0.U:

This variable conditionally defines the HAS_J0L symbol, which indicates to the C program that the j0l() routine is available.

"d_killpg"
From d_killpg.U:

This variable conditionally defines the "HAS_KILLPG" symbol, which indicates to the C program that the killpg() routine is available to kill process groups.

"d_lc_monetary_2008"
From d_lc_monetary_2008.U:

This variable conditionally defines HAS_LC_MONETARY_2008 if libc has the international currency locale rules from "POSIX" 1003.1-2008.

"d_lchown"
From d_lchown.U:

This variable conditionally defines the "HAS_LCHOWN" symbol, which indicates to the C program that the lchown() routine is available to operate on a symbolic link (instead of following the link).

"d_ldbl_dig"
From d_ldbl_dig.U:

This variable conditionally defines d_ldbl_dig if this system's header files provide "LDBL_DIG", which is the number of significant digits in a long double precision number.

"d_ldexpl"
From d_longdbl.U:

This variable conditionally defines the "HAS_LDEXPL" symbol, which indicates to the C program that the ldexpl() routine is available.

"d_lgamma"
From d_lgamma.U:

This variable conditionally defines the "HAS_LGAMMA" symbol, which indicates to the C program that the lgamma() routine is available for the log gamma function. See also d_tgamma and d_lgamma_r.

"d_lgamma_r"
From d_lgamma_r.U:

This variable conditionally defines the "HAS_LGAMMA_R" symbol, which indicates to the C program that the lgamma_r() routine is available for the log gamma function, without using the global signgam variable.

"d_libm_lib_version"
From d_libm_lib_version.U:

This variable conditionally defines the "LIBM_LIB_VERSION" symbol, which indicates to the C program that math.h defines "_LIB_VERSION" being available in libm

"d_libname_unique"
From so.U:

This variable is defined if the target system insists on unique basenames for shared library files. This is currently true on Android, false everywhere else we know of. Defaults to "undef".

"d_link"
From d_link.U:

This variable conditionally defines "HAS_LINK" if link() is available to create hard links.

"d_linkat"
From d_fsat.U:

This variable conditionally defines the "HAS_LINKAT" symbol, which indicates the "POSIX" linkat() function is available.

"d_llrint"
From d_llrint.U:

This variable conditionally defines the "HAS_LLRINT" symbol, which indicates to the C program that the llrint() routine is available to return the long long value closest to a double (according to the current rounding mode).

"d_llrintl"
From d_llrintl.U:

This variable conditionally defines the "HAS_LLRINTL" symbol, which indicates to the C program that the llrintl() routine is available to return the long long value closest to a long double (according to the current rounding mode).

"d_llround"
From d_llround.U:

This variable conditionally defines the "HAS_LLROUND" symbol, which indicates to the C program that the llround() routine is available to return the long long value nearest to x.

"d_llroundl"
From d_llroundl.U:

This variable conditionally defines the "HAS_LLROUNDL" symbol, which indicates to the C program that the llroundl() routine is available to return the long long value nearest to x away from zero.

"d_localeconv_l"
From d_localeconv_l.U:

This variable conditionally defines the "HAS_LOCALECONV_L" symbol, which indicates to the C program that the localeconv_l() routine is available.

"d_localtime64"
From d_timefuncs64.U:

This variable conditionally defines the HAS_LOCALTIME64 symbol, which indicates to the C program that the localtime64 () routine is available.

"d_localtime_r"
From d_localtime_r.U:

This variable conditionally defines the "HAS_LOCALTIME_R" symbol, which indicates to the C program that the localtime_r() routine is available.

"d_localtime_r_needs_tzset"
From d_localtime_r.U:

This variable conditionally defines the "LOCALTIME_R_NEEDS_TZSET" symbol, which makes us call tzset before localtime_r()

"d_locconv"
From d_locconv.U:

This variable conditionally defines "HAS_LOCALECONV" if localeconv() is available for numeric and monetary formatting conventions.

"d_lockf"
From d_lockf.U:

This variable conditionally defines "HAS_LOCKF" if lockf() is available to do file locking.

"d_log1p"
From d_log1p.U:

This variable conditionally defines the HAS_LOG1P symbol, which indicates to the C program that the logp1() routine is available to compute log(1 + x) for values of x close to zero.

"d_log2"
From d_log2.U:

This variable conditionally defines the HAS_LOG2 symbol, which indicates to the C program that the log2() routine is available to compute log base two.

"d_logb"
From d_logb.U:

This variable conditionally defines the "HAS_LOGB" symbol, which indicates to the C program that the logb() routine is available to extract the exponent of x.

"d_long_double_style_ieee"
From d_longdbl.U:

This variable conditionally defines "LONG_DOUBLE_STYLE_IEEE" if the long double is any of the "IEEE" 754 style long doubles: "LONG_DOUBLE_STYLE_IEEE_STD", "LONG_DOUBLE_STYLE_IEEE_EXTENDED", "LONG_DOUBLE_STYLE_IEEE_DOUBLEDOUBLE".

"d_long_double_style_ieee_doubledouble"
From d_longdbl.U:

This variable conditionally defines "LONG_DOUBLE_STYLE_IEEE_DOUBLEDOUBLE" if the long double is the 128-bit "IEEE" 754 double-double.

"d_long_double_style_ieee_extended"
From d_longdbl.U:

This variable conditionally defines "LONG_DOUBLE_STYLE_IEEE_EXTENDED" if the long double is the 80-bit "IEEE" 754 extended precision. Note that despite the "extended" this is less than the "std", since this is an extension of the double precision.

"d_long_double_style_ieee_std"
From d_longdbl.U:

This variable conditionally defines "LONG_DOUBLE_STYLE_IEEE_STD" if the long double is the 128-bit "IEEE" 754.

"d_long_double_style_vax"
From d_longdbl.U:

This variable conditionally defines "LONG_DOUBLE_STYLE_VAX" if the long double is the 128-bit "VAX" format H.

"d_longdbl"
From d_longdbl.U:

This variable conditionally defines "HAS_LONG_DOUBLE" if the long double type is supported.

"d_longlong"
From d_longlong.U:

This variable conditionally defines "HAS_LONG_LONG" if the long long type is supported.

"d_lrint"
From d_lrint.U:

This variable conditionally defines the "HAS_LRINT" symbol, which indicates to the C program that the lrint() routine is available to return the integral value closest to a double (according to the current rounding mode).

"d_lrintl"
From d_lrintl.U:

This variable conditionally defines the "HAS_LRINTL" symbol, which indicates to the C program that the lrintl() routine is available to return the integral value closest to a long double (according to the current rounding mode).

"d_lround"
From d_lround.U:

This variable conditionally defines the "HAS_LROUND" symbol, which indicates to the C program that the lround() routine is available to return the integral value nearest to x.

"d_lroundl"
From d_lroundl.U:

This variable conditionally defines the "HAS_LROUNDL" symbol, which indicates to the C program that the lroundl() routine is available to return the integral value nearest to x away from zero.

"d_lseekproto"
From d_lseekproto.U:

This variable conditionally defines the "HAS_LSEEK_PROTO" symbol, which indicates to the C program that the system provides a prototype for the lseek() function. Otherwise, it is up to the program to supply one.

"d_lstat"
From d_lstat.U:

This variable conditionally defines "HAS_LSTAT" if lstat() is available to do file stats on symbolic links.

"d_madvise"
From d_madvise.U:

This variable conditionally defines "HAS_MADVISE" if madvise() is available to map a file into memory.

"d_malloc_good_size"
From d_malloc_size.U:

This symbol, if defined, indicates that the malloc_good_size routine is available for use.

"d_malloc_size"
From d_malloc_size.U:

This symbol, if defined, indicates that the malloc_size routine is available for use.

"d_malloc_usable_size"
From d_malloc_size.U:

This symbol, if defined, indicates that the malloc_usable_size routine is available for use.

"d_mblen"
From d_mblen.U:

This variable conditionally defines the "HAS_MBLEN" symbol, which indicates to the C program that the mblen() routine is available to find the number of bytes in a multibyte character.

"d_mbrlen"
From d_mbrlen.U:

This variable conditionally defines the "HAS_MBRLEN" symbol if the mbrlen() routine is available to be used to get the length of multi-byte character strings.

"d_mbrtowc"
From d_mbrtowc.U:

This variable conditionally defines the "HAS_MBRTOWC" symbol if the mbrtowc() routine is available to be used to convert a multi-byte character into a wide character.

"d_mbstowcs"
From d_mbstowcs.U:

This variable conditionally defines the "HAS_MBSTOWCS" symbol, which indicates to the C program that the mbstowcs() routine is available to convert a multibyte string into a wide character string.

"d_mbtowc"
From d_mbtowc.U:

This variable conditionally defines the "HAS_MBTOWC" symbol, which indicates to the C program that the mbtowc() routine is available to convert multibyte to a wide character.

"d_memmem"
From d_memmem.U:

This variable conditionally defines the "HAS_MEMMEM" symbol, which indicates to the C program that the memmem() routine is available to return a pointer to the start of the first occurrence of a substring in a memory area (or "NULL" if not found).

"d_memrchr"
From d_memrchr.U:

This variable conditionally defines the "HAS_MEMRCHR" symbol, which indicates to the C program that the memrchr() routine is available to return a pointer to the last occurrence of a byte in a memory area (or "NULL" if not found).

"d_mkdir"
From d_mkdir.U:

This variable conditionally defines the "HAS_MKDIR" symbol, which indicates to the C program that the mkdir() routine is available to create directories..

"d_mkdtemp"
From d_mkdtemp.U:

This variable conditionally defines the "HAS_MKDTEMP" symbol, which indicates to the C program that the mkdtemp() routine is available to exclusively create a uniquely named temporary directory.

"d_mkfifo"
From d_mkfifo.U:

This variable conditionally defines the "HAS_MKFIFO" symbol, which indicates to the C program that the mkfifo() routine is available.

"d_mkostemp"
From d_mkostemp.U:

This variable conditionally defines "HAS_MKOSTEMP" if mkostemp() is available to exclusively create and open a uniquely named (with a suffix) temporary file.

"d_mkstemp"
From d_mkstemp.U:

This variable conditionally defines the "HAS_MKSTEMP" symbol, which indicates to the C program that the mkstemp() routine is available to exclusively create and open a uniquely named temporary file.

"d_mkstemps"
From d_mkstemps.U:

This variable conditionally defines the "HAS_MKSTEMPS" symbol, which indicates to the C program that the mkstemps() routine is available to exclusively create and open a uniquely named (with a suffix) temporary file.

"d_mktime"
From d_mktime.U:

This variable conditionally defines the "HAS_MKTIME" symbol, which indicates to the C program that the mktime() routine is available.

"d_mktime64"
From d_timefuncs64.U:

This variable conditionally defines the HAS_MKTIME64 symbol, which indicates to the C program that the mktime64 () routine is available.

"d_mmap"
From d_mmap.U:

This variable conditionally defines "HAS_MMAP" if mmap() is available to map a file into memory.

"d_modfl"
From d_modfl.U:

This variable conditionally defines the "HAS_MODFL" symbol, which indicates to the C program that the modfl() routine is available.

"d_modflproto"
From d_modfl.U:

This symbol, if defined, indicates that the system provides a prototype for the modfl() function. Otherwise, it is up to the program to supply one. C99 says it should be long double modfl(long double, long double *);

"d_mprotect"
From d_mprotect.U:

This variable conditionally defines "HAS_MPROTECT" if mprotect() is available to modify the access protection of a memory mapped file.

"d_msg"
From d_msg.U:

This variable conditionally defines the "HAS_MSG" symbol, which indicates that the entire msg*(2) library is present.

"d_msg_ctrunc"
From d_socket.U:

This variable conditionally defines the "HAS_MSG_CTRUNC" symbol, which indicates that the "MSG_CTRUNC" is available. #ifdef is not enough because it may be an enum, glibc has been known to do this.

"d_msg_dontroute"
From d_socket.U:

This variable conditionally defines the "HAS_MSG_DONTROUTE" symbol, which indicates that the "MSG_DONTROUTE" is available. #ifdef is not enough because it may be an enum, glibc has been known to do this.

"d_msg_oob"
From d_socket.U:

This variable conditionally defines the "HAS_MSG_OOB" symbol, which indicates that the "MSG_OOB" is available. #ifdef is not enough because it may be an enum, glibc has been known to do this.

"d_msg_peek"
From d_socket.U:

This variable conditionally defines the "HAS_MSG_PEEK" symbol, which indicates that the "MSG_PEEK" is available. #ifdef is not enough because it may be an enum, glibc has been known to do this.

"d_msg_proxy"
From d_socket.U:

This variable conditionally defines the "HAS_MSG_PROXY" symbol, which indicates that the "MSG_PROXY" is available. #ifdef is not enough because it may be an enum, glibc has been known to do this.

"d_msgctl"
From d_msgctl.U:

This variable conditionally defines the "HAS_MSGCTL" symbol, which indicates to the C program that the msgctl() routine is available.

"d_msgget"
From d_msgget.U:

This variable conditionally defines the "HAS_MSGGET" symbol, which indicates to the C program that the msgget() routine is available.

"d_msghdr_s"
From d_msghdr_s.U:

This variable conditionally defines the "HAS_STRUCT_MSGHDR" symbol, which indicates that the struct msghdr is supported.

"d_msgrcv"
From d_msgrcv.U:

This variable conditionally defines the "HAS_MSGRCV" symbol, which indicates to the C program that the msgrcv() routine is available.

"d_msgsnd"
From d_msgsnd.U:

This variable conditionally defines the "HAS_MSGSND" symbol, which indicates to the C program that the msgsnd() routine is available.

"d_msync"
From d_msync.U:

This variable conditionally defines "HAS_MSYNC" if msync() is available to synchronize a mapped file.

"d_munmap"
From d_munmap.U:

This variable conditionally defines "HAS_MUNMAP" if munmap() is available to unmap a region mapped by mmap().

"d_mymalloc"
From mallocsrc.U:

This variable conditionally defines "MYMALLOC" in case other parts of the source want to take special action if "MYMALLOC" is used. This may include different sorts of profiling or error detection.

"d_nan"
From d_nan.U:

This variable conditionally defines "HAS_NAN" if nan() is available to generate NaN.

"d_nanosleep"
From d_nanosleep.U:

This variable conditionally defines "HAS_NANOSLEEP" if nanosleep() is available to sleep with 1E-9 sec accuracy.

"d_ndbm"
From i_ndbm.U:

This variable conditionally defines the "HAS_NDBM" symbol, which indicates that both the ndbm.h include file and an appropriate ndbm library exist. Consult the different i_*ndbm variables to find out the actual include location. Sometimes, a system has the header file but not the library. This variable will only be set if the system has both.

"d_ndbm_h_uses_prototypes"
From i_ndbm.U:

This variable conditionally defines the "NDBM_H_USES_PROTOTYPES" symbol, which indicates that the ndbm.h include file uses real "ANSI" C prototypes instead of K&R style function declarations. K&R style declarations are unsupported in C++, so the include file requires special handling when using a C++ compiler and this variable is undefined. Consult the different d_*ndbm_h_uses_prototypes variables to get the same information for alternative ndbm.h include files.

"d_nearbyint"
From d_nearbyint.U:

This variable conditionally defines "HAS_NEARBYINT" if nearbyint() is available to return the integral value closest to (according to the current rounding mode) to x.

"d_newlocale"
From d_newlocale.U:

This variable conditionally defines the "HAS_NEWLOCALE" symbol, which indicates to the C program that the newlocale() routine is available to return a new locale object or modify an existing locale object.

"d_nextafter"
From d_nextafter.U:

This variable conditionally defines "HAS_NEXTAFTER" if nextafter() is available to return the next machine representable double from x in direction y.

"d_nexttoward"
From d_nexttoward.U:

This variable conditionally defines "HAS_NEXTTOWARD" if nexttoward() is available to return the next machine representable long double from x in direction y.

"d_nice"
From d_nice.U:

This variable conditionally defines the "HAS_NICE" symbol, which indicates to the C program that the nice() routine is available.

"d_nl_langinfo"
From d_nl_langinfo.U:

This variable conditionally defines the "HAS_NL_LANGINFO" symbol, which indicates to the C program that the nl_langinfo() routine is available.

"d_nv_preserves_uv"
From perlxv.U:

This variable indicates whether a variable of type nvtype can preserve all the bits a variable of type uvtype.

"d_nv_zero_is_allbits_zero"
From perlxv.U:

This variable indicates whether a variable of type nvtype stores 0.0 in memory as all bits zero.

"d_off64_t"
From d_off64_t.U:

This symbol will be defined if the C compiler supports off64_t.

"d_old_pthread_create_joinable"
From d_pthrattrj.U:

This variable conditionally defines pthread_create_joinable. undef if pthread.h defines "PTHREAD_CREATE_JOINABLE".

"d_oldpthreads"
From usethreads.U:

This variable conditionally defines the "OLD_PTHREADS_API" symbol, and indicates that Perl should be built to use the old draft "POSIX" threads "API". This is only potentially meaningful if usethreads is set.

"d_oldsock"
From d_socket.U:

This variable conditionally defines the "OLDSOCKET" symbol, which indicates that the "BSD" socket interface is based on 4.1c and not 4.2.

"d_open3"
From d_open3.U:

This variable conditionally defines the HAS_OPEN3 manifest constant, which indicates to the C program that the 3 argument version of the open(2) function is available.

"d_openat"
From d_fsat.U:

This variable conditionally defines the "HAS_OPENAT" symbol, which indicates the "POSIX" openat() function is available.

"d_pathconf"
From d_pathconf.U:

This variable conditionally defines the "HAS_PATHCONF" symbol, which indicates to the C program that the pathconf() routine is available to determine file-system related limits and options associated with a given filename.

"d_pause"
From d_pause.U:

This variable conditionally defines the "HAS_PAUSE" symbol, which indicates to the C program that the pause() routine is available to suspend a process until a signal is received.

"d_perl_otherlibdirs"
From otherlibdirs.U:

This variable conditionally defines "PERL_OTHERLIBDIRS", which contains a colon-separated set of paths for the perl binary to include in @"INC". See also otherlibdirs.

"d_phostname"
From d_gethname.U:

This variable conditionally defines the "HAS_PHOSTNAME" symbol, which contains the shell command which, when fed to popen(), may be used to derive the host name.

"d_pipe"
From d_pipe.U:

This variable conditionally defines the "HAS_PIPE" symbol, which indicates to the C program that the pipe() routine is available to create an inter-process channel.

"d_pipe2"
From d_pipe2.U:

This variable conditionally defines the HAS_PIPE2 symbol, which indicates to the C program that the pipe2() routine is available to create an inter-process channel.

"d_poll"
From d_poll.U:

This variable conditionally defines the "HAS_POLL" symbol, which indicates to the C program that the poll() routine is available to poll active file descriptors.

"d_portable"
From d_portable.U:

This variable conditionally defines the "PORTABLE" symbol, which indicates to the C program that it should not assume that it is running on the machine it was compiled on.

"d_prctl"
From d_prctl.U:

This variable conditionally defines the "HAS_PRCTL" symbol, which indicates to the C program that the prctl() routine is available. Note that there are at least two prctl variants: Linux and Irix. While they are somewhat similar, they are incompatible.

"d_prctl_set_name"
From d_prctl.U:

This variable conditionally defines the "HAS_PRCTL_SET_NAME" symbol, which indicates to the C program that the prctl() routine supports the "PR_SET_NAME" option.

"d_PRId64"
From quadfio.U:

This variable conditionally defines the PERL_PRId64 symbol, which indicates that stdio has a symbol to print 64-bit decimal numbers.

"d_PRIeldbl"
From longdblfio.U:

This variable conditionally defines the PERL_PRIfldbl symbol, which indicates that stdio has a symbol to print long doubles.

"d_PRIEUldbl"
From longdblfio.U:

This variable conditionally defines the PERL_PRIfldbl symbol, which indicates that stdio has a symbol to print long doubles. The "U" in the name is to separate this from d_PRIeldbl so that even case-blind systems can see the difference.

"d_PRIfldbl"
From longdblfio.U:

This variable conditionally defines the PERL_PRIfldbl symbol, which indicates that stdio has a symbol to print long doubles.

"d_PRIFUldbl"
From longdblfio.U:

This variable conditionally defines the PERL_PRIfldbl symbol, which indicates that stdio has a symbol to print long doubles. The "U" in the name is to separate this from d_PRIfldbl so that even case-blind systems can see the difference.

"d_PRIgldbl"
From longdblfio.U:

This variable conditionally defines the PERL_PRIfldbl symbol, which indicates that stdio has a symbol to print long doubles.

"d_PRIGUldbl"
From longdblfio.U:

This variable conditionally defines the PERL_PRIfldbl symbol, which indicates that stdio has a symbol to print long doubles. The "U" in the name is to separate this from d_PRIgldbl so that even case-blind systems can see the difference.

"d_PRIi64"
From quadfio.U:

This variable conditionally defines the PERL_PRIi64 symbol, which indicates that stdio has a symbol to print 64-bit decimal numbers.

"d_printf_format_null"
From d_attribut.U:

This variable conditionally defines "PRINTF_FORMAT_NULL_OK", which indicates the C compiler allows printf-like formats to be null.

"d_PRIo64"
From quadfio.U:

This variable conditionally defines the PERL_PRIo64 symbol, which indicates that stdio has a symbol to print 64-bit octal numbers.

"d_PRIu64"
From quadfio.U:

This variable conditionally defines the PERL_PRIu64 symbol, which indicates that stdio has a symbol to print 64-bit unsigned decimal numbers.

"d_PRIx64"
From quadfio.U:

This variable conditionally defines the PERL_PRIx64 symbol, which indicates that stdio has a symbol to print 64-bit hexadecimal numbers.

"d_PRIXU64"
From quadfio.U:

This variable conditionally defines the PERL_PRIXU64 symbol, which indicates that stdio has a symbol to print 64-bit hExADECimAl numbers. The "U" in the name is to separate this from d_PRIx64 so that even case-blind systems can see the difference.

"d_procselfexe"
From d_procselfexe.U:

Defined if $procselfexe is symlink to the absolute pathname of the executing program.

"d_pseudofork"
From d_vfork.U:

This variable conditionally defines the "HAS_PSEUDOFORK" symbol, which indicates that an emulation of the fork routine is available.

"d_pthread_atfork"
From d_pthread_atfork.U:

This variable conditionally defines the "HAS_PTHREAD_ATFORK" symbol, which indicates to the C program that the pthread_atfork() routine is available.

"d_pthread_attr_setscope"
From d_pthread_attr_ss.U:

This variable conditionally defines "HAS_PTHREAD_ATTR_SETSCOPE" if pthread_attr_setscope() is available to set the contention scope attribute of a thread attribute object.

"d_pthread_yield"
From d_pthread_y.U:

This variable conditionally defines the "HAS_PTHREAD_YIELD" symbol if the pthread_yield routine is available to yield the execution of the current thread.

"d_ptrdiff_t"
From d_ptrdiff_t.U:

This symbol will be defined if the C compiler supports ptrdiff_t.

"d_pwage"
From i_pwd.U:

This variable conditionally defines "PWAGE", which indicates that struct passwd contains pw_age.

"d_pwchange"
From i_pwd.U:

This variable conditionally defines "PWCHANGE", which indicates that struct passwd contains pw_change.

"d_pwclass"
From i_pwd.U:

This variable conditionally defines "PWCLASS", which indicates that struct passwd contains pw_class.

"d_pwcomment"
From i_pwd.U:

This variable conditionally defines "PWCOMMENT", which indicates that struct passwd contains pw_comment.

"d_pwexpire"
From i_pwd.U:

This variable conditionally defines "PWEXPIRE", which indicates that struct passwd contains pw_expire.

"d_pwgecos"
From i_pwd.U:

This variable conditionally defines "PWGECOS", which indicates that struct passwd contains pw_gecos.

"d_pwpasswd"
From i_pwd.U:

This variable conditionally defines "PWPASSWD", which indicates that struct passwd contains pw_passwd.

"d_pwquota"
From i_pwd.U:

This variable conditionally defines "PWQUOTA", which indicates that struct passwd contains pw_quota.

"d_qgcvt"
From d_qgcvt.U:

This variable conditionally defines the "HAS_QGCVT" symbol, which indicates to the C program that the qgcvt() routine is available.

"d_quad"
From quadtype.U:

This variable, if defined, tells that there's a 64-bit integer type, quadtype.

"d_querylocale"
From d_newlocale.U:

This variable conditionally defines the "HAS_QUERYLOCALE" symbol, which indicates to the C program that the querylocale() routine is available to return the name of the locale for a category mask.

"d_random_r"
From d_random_r.U:

This variable conditionally defines the "HAS_RANDOM_R" symbol, which indicates to the C program that the random_r() routine is available.

"d_re_comp"
From d_regcmp.U:

This variable conditionally defines the "HAS_RECOMP" symbol, which indicates to the C program that the re_comp() routine is available for regular pattern matching (usually on "BSD"). If so, it is likely that re_exec() exists.

"d_readdir"
From d_readdir.U:

This variable conditionally defines "HAS_READDIR" if readdir() is available to read directory entries.

"d_readdir64_r"
From d_readdir64_r.U:

This variable conditionally defines the HAS_READDIR64_R symbol, which indicates to the C program that the readdir64_r() routine is available.

"d_readdir_r"
From d_readdir_r.U:

This variable conditionally defines the "HAS_READDIR_R" symbol, which indicates to the C program that the readdir_r() routine is available.

"d_readlink"
From d_readlink.U:

This variable conditionally defines the "HAS_READLINK" symbol, which indicates to the C program that the readlink() routine is available to read the value of a symbolic link.

"d_readv"
From d_readv.U:

This variable conditionally defines the "HAS_READV" symbol, which indicates to the C program that the readv() routine is available.

"d_recvmsg"
From d_recvmsg.U:

This variable conditionally defines the "HAS_RECVMSG" symbol, which indicates to the C program that the recvmsg() routine is available.

"d_regcmp"
From d_regcmp.U:

This variable conditionally defines the "HAS_REGCMP" symbol, which indicates to the C program that the regcmp() routine is available for regular pattern matching (usually on System V).

"d_regcomp"
From d_regcmp.U:

This variable conditionally defines the "HAS_REGCOMP" symbol, which indicates to the C program that the regcomp() routine is available for regular pattern matching (usually on POSIX.2 conforming systems).

"d_remainder"
From d_remainder.U:

This variable conditionally defines the "HAS_REMAINDER" symbol, which indicates to the C program that the remainder() routine is available.

"d_remquo"
From d_remquo.U:

This variable conditionally defines the "HAS_REMQUO" symbol, which indicates to the C program that the remquo() routine is available.

"d_rename"
From d_rename.U:

This variable conditionally defines the "HAS_RENAME" symbol, which indicates to the C program that the rename() routine is available to rename files.

"d_renameat"
From d_fsat.U:

This variable conditionally defines the "HAS_RENAMEAT" symbol, which indicates the "POSIX" renameat() function is available.

"d_rewinddir"
From d_readdir.U:

This variable conditionally defines "HAS_REWINDDIR" if rewinddir() is available.

"d_rint"
From d_rint.U:

This variable conditionally defines the "HAS_RINT" symbol, which indicates to the C program that the rint() routine is available.

"d_rmdir"
From d_rmdir.U:

This variable conditionally defines "HAS_RMDIR" if rmdir() is available to remove directories.

"d_round"
From d_round.U:

This variable conditionally defines the "HAS_ROUND" symbol, which indicates to the C program that the round() routine is available.

"d_sbrkproto"
From d_sbrkproto.U:

This variable conditionally defines the "HAS_SBRK_PROTO" symbol, which indicates to the C program that the system provides a prototype for the sbrk() function. Otherwise, it is up to the program to supply one.

"d_scalbn"
From d_scalbn.U:

This variable conditionally defines the "HAS_SCALBN" symbol, which indicates to the C program that the scalbn() routine is available.

"d_scalbnl"
From d_scalbnl.U:

This variable conditionally defines the "HAS_SCALBNL" symbol, which indicates to the C program that the scalbnl() routine is available. If ilogbl is also present we can emulate frexpl.

"d_sched_yield"
From d_pthread_y.U:

This variable conditionally defines the "HAS_SCHED_YIELD" symbol if the sched_yield routine is available to yield the execution of the current thread.

"d_scm_rights"
From d_socket.U:

This variable conditionally defines the "HAS_SCM_RIGHTS" symbol, which indicates that the "SCM_RIGHTS" is available. #ifdef is not enough because it may be an enum, glibc has been known to do this.

"d_SCNfldbl"
From longdblfio.U:

This variable conditionally defines the PERL_PRIfldbl symbol, which indicates that stdio has a symbol to scan long doubles.

"d_seekdir"
From d_readdir.U:

This variable conditionally defines "HAS_SEEKDIR" if seekdir() is available.

"d_select"
From d_select.U:

This variable conditionally defines "HAS_SELECT" if select() is available to select active file descriptors. A <sys/time.h> inclusion may be necessary for the timeout field.

"d_sem"
From d_sem.U:

This variable conditionally defines the "HAS_SEM" symbol, which indicates that the entire sem*(2) library is present.

"d_semctl"
From d_semctl.U:

This variable conditionally defines the "HAS_SEMCTL" symbol, which indicates to the C program that the semctl() routine is available.

"d_semctl_semid_ds"
From d_union_semun.U:

This variable conditionally defines "USE_SEMCTL_SEMID_DS", which indicates that struct semid_ds * is to be used for semctl "IPC_STAT".

"d_semctl_semun"
From d_union_semun.U:

This variable conditionally defines "USE_SEMCTL_SEMUN", which indicates that union semun is to be used for semctl "IPC_STAT".

"d_semget"
From d_semget.U:

This variable conditionally defines the "HAS_SEMGET" symbol, which indicates to the C program that the semget() routine is available.

"d_semop"
From d_semop.U:

This variable conditionally defines the "HAS_SEMOP" symbol, which indicates to the C program that the semop() routine is available.

"d_sendmsg"
From d_sendmsg.U:

This variable conditionally defines the "HAS_SENDMSG" symbol, which indicates to the C program that the sendmsg() routine is available.

"d_setegid"
From d_setegid.U:

This variable conditionally defines the "HAS_SETEGID" symbol, which indicates to the C program that the setegid() routine is available to change the effective gid of the current program.

"d_seteuid"
From d_seteuid.U:

This variable conditionally defines the "HAS_SETEUID" symbol, which indicates to the C program that the seteuid() routine is available to change the effective uid of the current program.

"d_setgrent"
From d_setgrent.U:

This variable conditionally defines the "HAS_SETGRENT" symbol, which indicates to the C program that the setgrent() routine is available for initializing sequential access to the group database.

"d_setgrent_r"
From d_setgrent_r.U:

This variable conditionally defines the "HAS_SETGRENT_R" symbol, which indicates to the C program that the setgrent_r() routine is available.

"d_setgrps"
From d_setgrps.U:

This variable conditionally defines the "HAS_SETGROUPS" symbol, which indicates to the C program that the setgroups() routine is available to set the list of process groups.

"d_sethent"
From d_sethent.U:

This variable conditionally defines "HAS_SETHOSTENT" if sethostent() is available.

"d_sethostent_r"
From d_sethostent_r.U:

This variable conditionally defines the "HAS_SETHOSTENT_R" symbol, which indicates to the C program that the sethostent_r() routine is available.

"d_setitimer"
From d_setitimer.U:

This variable conditionally defines the "HAS_SETITIMER" symbol, which indicates to the C program that the setitimer() routine is available.

"d_setlinebuf"
From d_setlnbuf.U:

This variable conditionally defines the "HAS_SETLINEBUF" symbol, which indicates to the C program that the setlinebuf() routine is available to change stderr or stdout from block-buffered or unbuffered to a line-buffered mode.

"d_setlocale"
From d_setlocale.U:

This variable conditionally defines "HAS_SETLOCALE" if setlocale() is available to handle locale-specific ctype implementations.

"d_setlocale_accepts_any_locale_name"
From d_setlocale.U:

This variable conditionally defines "SETLOCALE_ACCEPTS_ANY_LOCALE_NAME" if setlocale() accepts any locale name.

"d_setlocale_r"
From d_setlocale_r.U:

This variable conditionally defines the "HAS_SETLOCALE_R" symbol, which indicates to the C program that the setlocale_r() routine is available.

"d_setnent"
From d_setnent.U:

This variable conditionally defines "HAS_SETNETENT" if setnetent() is available.

"d_setnetent_r"
From d_setnetent_r.U:

This variable conditionally defines the "HAS_SETNETENT_R" symbol, which indicates to the C program that the setnetent_r() routine is available.

"d_setpent"
From d_setpent.U:

This variable conditionally defines "HAS_SETPROTOENT" if setprotoent() is available.

"d_setpgid"
From d_setpgid.U:

This variable conditionally defines the "HAS_SETPGID" symbol if the setpgid(pid, gpid) function is available to set process group "ID".

"d_setpgrp"
From d_setpgrp.U:

This variable conditionally defines "HAS_SETPGRP" if setpgrp() is available to set the current process group.

"d_setpgrp2"
From d_setpgrp2.U:

This variable conditionally defines the HAS_SETPGRP2 symbol, which indicates to the C program that the setpgrp2() (as in DG/"UX") routine is available to set the current process group.

"d_setprior"
From d_setprior.U:

This variable conditionally defines "HAS_SETPRIORITY" if setpriority() is available to set a process's priority.

"d_setproctitle"
From d_setproctitle.U:

This variable conditionally defines the "HAS_SETPROCTITLE" symbol, which indicates to the C program that the setproctitle() routine is available.

"d_setprotoent_r"
From d_setprotoent_r.U:

This variable conditionally defines the "HAS_SETPROTOENT_R" symbol, which indicates to the C program that the setprotoent_r() routine is available.

"d_setpwent"
From d_setpwent.U:

This variable conditionally defines the "HAS_SETPWENT" symbol, which indicates to the C program that the setpwent() routine is available for initializing sequential access to the passwd database.

"d_setpwent_r"
From d_setpwent_r.U:

This variable conditionally defines the "HAS_SETPWENT_R" symbol, which indicates to the C program that the setpwent_r() routine is available.

"d_setregid"
From d_setregid.U:

This variable conditionally defines "HAS_SETREGID" if setregid() is available to change the real and effective gid of the current process.

"d_setresgid"
From d_setregid.U:

This variable conditionally defines "HAS_SETRESGID" if setresgid() is available to change the real, effective and saved gid of the current process.

"d_setresuid"
From d_setreuid.U:

This variable conditionally defines "HAS_SETREUID" if setresuid() is available to change the real, effective and saved uid of the current process.

"d_setreuid"
From d_setreuid.U:

This variable conditionally defines "HAS_SETREUID" if setreuid() is available to change the real and effective uid of the current process.

"d_setrgid"
From d_setrgid.U:

This variable conditionally defines the "HAS_SETRGID" symbol, which indicates to the C program that the setrgid() routine is available to change the real gid of the current program.

"d_setruid"
From d_setruid.U:

This variable conditionally defines the "HAS_SETRUID" symbol, which indicates to the C program that the setruid() routine is available to change the real uid of the current program.

"d_setsent"
From d_setsent.U:

This variable conditionally defines "HAS_SETSERVENT" if setservent() is available.

"d_setservent_r"
From d_setservent_r.U:

This variable conditionally defines the "HAS_SETSERVENT_R" symbol, which indicates to the C program that the setservent_r() routine is available.

"d_setsid"
From d_setsid.U:

This variable conditionally defines "HAS_SETSID" if setsid() is available to set the process group "ID".

"d_setvbuf"
From d_setvbuf.U:

This variable conditionally defines the "HAS_SETVBUF" symbol, which indicates to the C program that the setvbuf() routine is available to change buffering on an open stdio stream.

"d_shm"
From d_shm.U:

This variable conditionally defines the "HAS_SHM" symbol, which indicates that the entire shm*(2) library is present.

"d_shmat"
From d_shmat.U:

This variable conditionally defines the "HAS_SHMAT" symbol, which indicates to the C program that the shmat() routine is available.

"d_shmatprototype"
From d_shmat.U:

This variable conditionally defines the "HAS_SHMAT_PROTOTYPE" symbol, which indicates that sys/shm.h has a prototype for shmat.

"d_shmctl"
From d_shmctl.U:

This variable conditionally defines the "HAS_SHMCTL" symbol, which indicates to the C program that the shmctl() routine is available.

"d_shmdt"
From d_shmdt.U:

This variable conditionally defines the "HAS_SHMDT" symbol, which indicates to the C program that the shmdt() routine is available.

"d_shmget"
From d_shmget.U:

This variable conditionally defines the "HAS_SHMGET" symbol, which indicates to the C program that the shmget() routine is available.

"d_sigaction"
From d_sigaction.U:

This variable conditionally defines the "HAS_SIGACTION" symbol, which indicates that the Vr4 sigaction() routine is available.

"d_siginfo_si_addr"
From d_siginfo_si.U:

This variable conditionally defines the "HAS_SIGINFO_SI_ADDR" symbol, which indicates that the siginfo_t struct has the si_addr member.

"d_siginfo_si_band"
From d_siginfo_si.U:

This variable conditionally defines the "HAS_SIGINFO_SI_BAND" symbol, which indicates that the siginfo_t struct has the si_band member.

"d_siginfo_si_errno"
From d_siginfo_si.U:

This variable conditionally defines the "HAS_SIGINFO_SI_ERRNO" symbol, which indicates that the siginfo_t struct has the si_errno member.

"d_siginfo_si_fd"
From d_siginfo_si.U:

This variable conditionally defines the "HAS_SIGINFO_SI_FD" symbol, which indicates that the siginfo_t struct has the si_fd member.

"d_siginfo_si_pid"
From d_siginfo_si.U:

This variable conditionally defines the "HAS_SIGINFO_SI_PID" symbol, which indicates that the siginfo_t struct has the si_pid member.

"d_siginfo_si_status"
From d_siginfo_si.U:

This variable conditionally defines the "HAS_SIGINFO_SI_STATUS" symbol, which indicates that the siginfo_t struct has the si_status member.

"d_siginfo_si_uid"
From d_siginfo_si.U:

This variable conditionally defines the "HAS_SIGINFO_SI_UID" symbol, which indicates that the siginfo_t struct has the si_uid member.

"d_siginfo_si_value"
From d_siginfo_si.U:

This variable conditionally defines the "HAS_SIGINFO_SI_VALUE" symbol, which indicates that the siginfo_t struct has the si_value member.

"d_signbit"
From d_signbit.U:

This variable conditionally defines the "HAS_SIGNBIT" symbol, which indicates to the C program that the signbit() routine is available and safe to use with perl's intern "NV" type.

"d_sigprocmask"
From d_sigprocmask.U:

This variable conditionally defines "HAS_SIGPROCMASK" if sigprocmask() is available to examine or change the signal mask of the calling process.

"d_sigsetjmp"
From d_sigsetjmp.U:

This variable conditionally defines the "HAS_SIGSETJMP" symbol, which indicates that the sigsetjmp() routine is available to call setjmp() and optionally save the process's signal mask.

"d_sin6_scope_id"
From d_socket.U:

This variable conditionally defines the HAS_SIN6_SCOPE_ID symbol, which indicates that a struct sockaddr_in6 structure has the sin6_scope_id member.

"d_sitearch"
From sitearch.U:

This variable conditionally defines "SITEARCH" to hold the pathname of architecture-dependent library files for $package. If $sitearch is the same as $archlib, then this is set to undef.

"d_snprintf"
From d_snprintf.U:

This variable conditionally defines the "HAS_SNPRINTF" symbol, which indicates to the C program that the snprintf () library function is available.

"d_sockaddr_in6"
From d_socket.U:

This variable conditionally defines the HAS_SOCKADDR_IN6 symbol, which indicates the availability of a struct sockaddr_in6.

"d_sockaddr_sa_len"
From d_socket.U:

This variable conditionally defines the "HAS_SOCKADDR_SA_LEN" symbol, which indicates that a struct sockaddr structure has the sa_len member.

"d_sockaddr_storage"
From d_socket.U:

This variable conditionally defines the "HAS_SOCKADDR_STORAGE" symbol, which indicates the availability of a struct sockaddr_storage.

"d_sockatmark"
From d_sockatmark.U:

This variable conditionally defines the "HAS_SOCKATMARK" symbol, which indicates to the C program that the sockatmark() routine is available.

"d_sockatmarkproto"
From d_sockatmarkproto.U:

This variable conditionally defines the "HAS_SOCKATMARK_PROTO" symbol, which indicates to the C program that the system provides a prototype for the sockatmark() function. Otherwise, it is up to the program to supply one.

"d_socket"
From d_socket.U:

This variable conditionally defines "HAS_SOCKET", which indicates that the "BSD" socket interface is supported.

"d_socklen_t"
From d_socklen_t.U:

This symbol will be defined if the C compiler supports socklen_t.

"d_sockpair"
From d_socket.U:

This variable conditionally defines the "HAS_SOCKETPAIR" symbol, which indicates that the "BSD" socketpair() is supported.

"d_socks5_init"
From d_socks5_init.U:

This variable conditionally defines the HAS_SOCKS5_INIT symbol, which indicates to the C program that the socks5_init() routine is available.

"d_sqrtl"
From d_sqrtl.U:

This variable conditionally defines the "HAS_SQRTL" symbol, which indicates to the C program that the sqrtl() routine is available.

"d_srand48_r"
From d_srand48_r.U:

This variable conditionally defines the HAS_SRAND48_R symbol, which indicates to the C program that the srand48_r() routine is available.

"d_srandom_r"
From d_srandom_r.U:

This variable conditionally defines the "HAS_SRANDOM_R" symbol, which indicates to the C program that the srandom_r() routine is available.

"d_sresgproto"
From d_sresgproto.U:

This variable conditionally defines the "HAS_SETRESGID_PROTO" symbol, which indicates to the C program that the system provides a prototype for the setresgid() function. Otherwise, it is up to the program to supply one.

"d_sresuproto"
From d_sresuproto.U:

This variable conditionally defines the "HAS_SETRESUID_PROTO" symbol, which indicates to the C program that the system provides a prototype for the setresuid() function. Otherwise, it is up to the program to supply one.

"d_stat"
From d_stat.U:

This variable conditionally defines "HAS_STAT" if stat() is available to get file status.

"d_statblks"
From d_statblks.U:

This variable conditionally defines "USE_STAT_BLOCKS" if this system has a stat structure declaring st_blksize and st_blocks.

"d_statfs_f_flags"
From d_statfs_f_flags.U:

This variable conditionally defines the "HAS_STRUCT_STATFS_F_FLAGS" symbol, which indicates to struct statfs from has f_flags member. This kind of struct statfs is coming from sys/mount.h ("BSD"), not from sys/statfs.h ("SYSV").

"d_statfs_s"
From d_statfs_s.U:

This variable conditionally defines the "HAS_STRUCT_STATFS" symbol, which indicates that the struct statfs is supported.

"d_static_inline"
From d_static_inline.U:

This variable conditionally defines the "HAS_STATIC_INLINE" symbol, which indicates that the C compiler supports C99-style static inline. That is, the function can't be called from another translation unit.

"d_statvfs"
From d_statvfs.U:

This variable conditionally defines the "HAS_STATVFS" symbol, which indicates to the C program that the statvfs() routine is available.

"d_stdio_cnt_lval"
From d_stdstdio.U:

This variable conditionally defines "STDIO_CNT_LVALUE" if the "FILE_cnt" macro can be used as an lvalue.

"d_stdio_ptr_lval"
From d_stdstdio.U:

This variable conditionally defines "STDIO_PTR_LVALUE" if the "FILE_ptr" macro can be used as an lvalue.

"d_stdio_ptr_lval_nochange_cnt"
From d_stdstdio.U:

This symbol is defined if using the "FILE_ptr" macro as an lvalue to increase the pointer by n leaves File_cnt(fp) unchanged.

"d_stdio_ptr_lval_sets_cnt"
From d_stdstdio.U:

This symbol is defined if using the "FILE_ptr" macro as an lvalue to increase the pointer by n has the side effect of decreasing the value of File_cnt(fp) by n.

"d_stdio_stream_array"
From stdio_streams.U:

This variable tells whether there is an array holding the stdio streams.

"d_stdiobase"
From d_stdstdio.U:

This variable conditionally defines "USE_STDIO_BASE" if this system has a "FILE" structure declaring a usable _base field (or equivalent) in stdio.h.

"d_stdstdio"
From d_stdstdio.U:

This variable conditionally defines "USE_STDIO_PTR" if this system has a "FILE" structure declaring usable _ptr and _cnt fields (or equivalent) in stdio.h.

"d_strcoll"
From d_strcoll.U:

This variable conditionally defines "HAS_STRCOLL" if strcoll() is available to compare strings using collating information.

"d_strerror_l"
From d_strerror_l.U:

This variable conditionally defines the "HAS_STRERROR_L" symbol, which indicates to the C program that the strerror_l() routine is available to return the error message for a given errno value in a particular locale (identified by a locale_t object).

"d_strerror_r"
From d_strerror_r.U:

This variable conditionally defines the "HAS_STRERROR_R" symbol, which indicates to the C program that the strerror_r() routine is available.

"d_strftime"
From d_strftime.U:

This variable conditionally defines the "HAS_STRFTIME" symbol, which indicates to the C program that the strftime() routine is available.

"d_strlcat"
From d_strlcat.U:

This variable conditionally defines the "HAS_STRLCAT" symbol, which indicates to the C program that the strlcat () routine is available.

"d_strlcpy"
From d_strlcpy.U:

This variable conditionally defines the "HAS_STRLCPY" symbol, which indicates to the C program that the strlcpy () routine is available.

"d_strnlen"
From d_strnlen.U:

This variable conditionally defines the "HAS_STRNLEN" symbol, which indicates to the C program that the strnlen () routine is available.

"d_strtod"
From d_strtod.U:

This variable conditionally defines the "HAS_STRTOD" symbol, which indicates to the C program that the strtod() routine is available to provide better numeric string conversion than atof().

"d_strtod_l"
From d_strtod_l.U:

This variable conditionally defines the "HAS_STRTOD_L" symbol, which indicates to the C program that the strtod_l() routine is available.

"d_strtol"
From d_strtol.U:

This variable conditionally defines the "HAS_STRTOL" symbol, which indicates to the C program that the strtol() routine is available to provide better numeric string conversion than atoi() and friends.

"d_strtold"
From d_strtold.U:

This variable conditionally defines the "HAS_STRTOLD" symbol, which indicates to the C program that the strtold() routine is available.

"d_strtold_l"
From d_strtold_l.U:

This variable conditionally defines the "HAS_STRTOLD_L" symbol, which indicates to the C program that the strtold_l() routine is available.

"d_strtoll"
From d_strtoll.U:

This variable conditionally defines the "HAS_STRTOLL" symbol, which indicates to the C program that the strtoll() routine is available.

"d_strtoq"
From d_strtoq.U:

This variable conditionally defines the "HAS_STRTOQ" symbol, which indicates to the C program that the strtoq() routine is available.

"d_strtoul"
From d_strtoul.U:

This variable conditionally defines the "HAS_STRTOUL" symbol, which indicates to the C program that the strtoul() routine is available to provide conversion of strings to unsigned long.

"d_strtoull"
From d_strtoull.U:

This variable conditionally defines the "HAS_STRTOULL" symbol, which indicates to the C program that the strtoull() routine is available.

"d_strtouq"
From d_strtouq.U:

This variable conditionally defines the "HAS_STRTOUQ" symbol, which indicates to the C program that the strtouq() routine is available.

"d_strxfrm"
From d_strxfrm.U:

This variable conditionally defines "HAS_STRXFRM" if strxfrm() is available to transform strings.

"d_suidsafe"
From d_dosuid.U:

This variable conditionally defines "SETUID_SCRIPTS_ARE_SECURE_NOW" if setuid scripts can be secure. This test looks in /dev/fd/.

"d_symlink"
From d_symlink.U:

This variable conditionally defines the "HAS_SYMLINK" symbol, which indicates to the C program that the symlink() routine is available to create symbolic links.

"d_syscall"
From d_syscall.U:

This variable conditionally defines "HAS_SYSCALL" if syscall() is available call arbitrary system calls.

"d_syscallproto"
From d_syscallproto.U:

This variable conditionally defines the "HAS_SYSCALL_PROTO" symbol, which indicates to the C program that the system provides a prototype for the syscall() function. Otherwise, it is up to the program to supply one.

"d_sysconf"
From d_sysconf.U:

This variable conditionally defines the "HAS_SYSCONF" symbol, which indicates to the C program that the sysconf() routine is available to determine system related limits and options.

"d_sysernlst"
From d_strerror.U:

This variable conditionally defines "HAS_SYS_ERRNOLIST" if sys_errnolist[] is available to translate error numbers to the symbolic name.

"d_syserrlst"
From d_strerror.U:

This variable conditionally defines "HAS_SYS_ERRLIST" if sys_errlist[] is available to translate error numbers to strings.

"d_system"
From d_system.U:

This variable conditionally defines "HAS_SYSTEM" if system() is available to issue a shell command.

"d_tcgetpgrp"
From d_tcgtpgrp.U:

This variable conditionally defines the "HAS_TCGETPGRP" symbol, which indicates to the C program that the tcgetpgrp() routine is available. to get foreground process group "ID".

"d_tcsetpgrp"
From d_tcstpgrp.U:

This variable conditionally defines the "HAS_TCSETPGRP" symbol, which indicates to the C program that the tcsetpgrp() routine is available to set foreground process group "ID".

"d_telldir"
From d_readdir.U:

This variable conditionally defines "HAS_TELLDIR" if telldir() is available.

"d_telldirproto"
From d_telldirproto.U:

This variable conditionally defines the "HAS_TELLDIR_PROTO" symbol, which indicates to the C program that the system provides a prototype for the telldir() function. Otherwise, it is up to the program to supply one.

"d_tgamma"
From d_tgamma.U:

This variable conditionally defines the "HAS_TGAMMA" symbol, which indicates to the C program that the tgamma() routine is available for the gamma function. See also d_lgamma.

"d_thread_safe_nl_langinfo_l"
From d_nl_langinfo_l.U:

This variable contains the eventual value of the "HAS_THREAD_SAFE_NL_LANGINFO_L" symbol, which indicates if the nl_langinfo_l() function exists and is thread-safe.

"d_time"
From d_time.U:

This variable conditionally defines the "HAS_TIME" symbol, which indicates that the time() routine exists. The time() routine is normally provided on "UNIX" systems.

"d_timegm"
From d_timegm.U:

This variable conditionally defines the "HAS_TIMEGM" symbol, which indicates to the C program that the timegm () routine is available.

"d_times"
From d_times.U:

This variable conditionally defines the "HAS_TIMES" symbol, which indicates that the times() routine exists. The times() routine is normally provided on "UNIX" systems. You may have to include <sys/times.h>.

"d_tm_tm_gmtoff"
From i_time.U:

This variable conditionally defines "HAS_TM_TM_GMTOFF", which indicates to the C program that the struct tm has the tm_gmtoff field.

"d_tm_tm_zone"
From i_time.U:

This variable conditionally defines "HAS_TM_TM_ZONE", which indicates to the C program that the struct tm has the tm_zone field.

"d_tmpnam_r"
From d_tmpnam_r.U:

This variable conditionally defines the "HAS_TMPNAM_R" symbol, which indicates to the C program that the tmpnam_r() routine is available.

"d_towlower"
From d_towlower.U:

This variable conditionally defines the "HAS_TOWLOWER" symbol, which indicates to the C program that the towlower() routine is available.

"d_towupper"
From d_towupper.U:

This variable conditionally defines the "HAS_TOWUPPER" symbol, which indicates to the C program that the towupper() routine is available.

"d_trunc"
From d_trunc.U:

This variable conditionally defines the "HAS_TRUNC" symbol, which indicates to the C program that the trunc() routine is available to round doubles towards zero.

"d_truncate"
From d_truncate.U:

This variable conditionally defines "HAS_TRUNCATE" if truncate() is available to truncate files.

"d_truncl"
From d_truncl.U:

This variable conditionally defines the "HAS_TRUNCL" symbol, which indicates to the C program that the truncl() routine is available to round long doubles towards zero. If copysignl is also present, we can emulate modfl.

"d_ttyname_r"
From d_ttyname_r.U:

This variable conditionally defines the "HAS_TTYNAME_R" symbol, which indicates to the C program that the ttyname_r() routine is available.

"d_tzname"
From d_tzname.U:

This variable conditionally defines "HAS_TZNAME" if tzname[] is available to access timezone names.

"d_u32align"
From d_u32align.U:

This variable tells whether you must access character data through U32-aligned pointers.

"d_ualarm"
From d_ualarm.U:

This variable conditionally defines the "HAS_UALARM" symbol, which indicates to the C program that the ualarm() routine is available.

"d_umask"
From d_umask.U:

This variable conditionally defines the "HAS_UMASK" symbol, which indicates to the C program that the umask() routine is available. to set and get the value of the file creation mask.

"d_uname"
From d_gethname.U:

This variable conditionally defines the "HAS_UNAME" symbol, which indicates to the C program that the uname() routine may be used to derive the host name.

"d_union_semun"
From d_union_semun.U:

This variable conditionally defines "HAS_UNION_SEMUN" if the union semun is defined by including <sys/sem.h>.

"d_unlinkat"
From d_fsat.U:

This variable conditionally defines the "HAS_UNLINKAT" symbol, which indicates the "POSIX" unlinkat() function isavailable.

"d_unordered"
From d_unordered.U:

This variable conditionally defines the "HAS_UNORDERED" symbol, which indicates to the C program that the unordered() routine is available.

"d_unsetenv"
From d_unsetenv.U:

This variable conditionally defines the "HAS_UNSETENV" symbol, which indicates to the C program that the unsetenv () routine is available.

"d_uselocale"
From d_newlocale.U:

This variable conditionally defines the "HAS_USELOCALE" symbol, which indicates to the C program that the uselocale() routine is available to set the current locale for the calling thread.

"d_usleep"
From d_usleep.U:

This variable conditionally defines "HAS_USLEEP" if usleep() is available to do high granularity sleeps.

"d_usleepproto"
From d_usleepproto.U:

This variable conditionally defines the "HAS_USLEEP_PROTO" symbol, which indicates to the C program that the system provides a prototype for the usleep() function. Otherwise, it is up to the program to supply one.

"d_ustat"
From d_ustat.U:

This variable conditionally defines "HAS_USTAT" if ustat() is available to query file system statistics by dev_t.

"d_vendorarch"
From vendorarch.U:

This variable conditionally defined "PERL_VENDORARCH".

"d_vendorbin"
From vendorbin.U:

This variable conditionally defines "PERL_VENDORBIN".

"d_vendorlib"
From vendorlib.U:

This variable conditionally defines "PERL_VENDORLIB".

"d_vendorscript"
From vendorscript.U:

This variable conditionally defines "PERL_VENDORSCRIPT".

"d_vfork"
From d_vfork.U:

This variable conditionally defines the "HAS_VFORK" symbol, which indicates the vfork() routine is available.

"d_void_closedir"
From d_closedir.U:

This variable conditionally defines "VOID_CLOSEDIR" if closedir() does not return a value.

"d_voidsig"
From d_voidsig.U:

This variable conditionally defines "VOIDSIG" if this system declares "void (*signal(...))()" in signal.h. The old way was to declare it as "int (*signal(...))()".

"d_voidtty"
From i_sysioctl.U:

This variable conditionally defines "USE_IOCNOTTY" to indicate that the ioctl() call with "TIOCNOTTY" should be used to void tty association. Otherwise (on "USG" probably), it is enough to close the standard file descriptors and do a setpgrp().

"d_vsnprintf"
From d_snprintf.U:

This variable conditionally defines the "HAS_VSNPRINTF" symbol, which indicates to the C program that the vsnprintf () library function is available.

"d_wait4"
From d_wait4.U:

This variable conditionally defines the HAS_WAIT4 symbol, which indicates the wait4() routine is available.

"d_waitpid"
From d_waitpid.U:

This variable conditionally defines "HAS_WAITPID" if waitpid() is available to wait for child process.

"d_wcrtomb"
From d_wcrtomb.U:

This variable conditionally defines the "HAS_WCRTOMB" symbol if the wcrtomb() routine is available to be used to convert a wide character into a multi-byte character.

"d_wcscmp"
From d_wcscmp.U:

This variable conditionally defines the "HAS_WCSCMP" symbol if the wcscmp() routine is available and can be used to compare wide character strings.

"d_wcstombs"
From d_wcstombs.U:

This variable conditionally defines the "HAS_WCSTOMBS" symbol, which indicates to the C program that the wcstombs() routine is available to convert wide character strings to multibyte strings.

"d_wcsxfrm"
From d_wcsxfrm.U:

This variable conditionally defines the "HAS_WCSXFRM" symbol if the wcsxfrm() routine is available and can be used to compare wide character strings.

"d_wctomb"
From d_wctomb.U:

This variable conditionally defines the "HAS_WCTOMB" symbol, which indicates to the C program that the wctomb() routine is available to convert a wide character to a multibyte.

"d_writev"
From d_writev.U:

This variable conditionally defines the "HAS_WRITEV" symbol, which indicates to the C program that the writev() routine is available.

"d_xenix"
From Guess.U:

This variable conditionally defines the symbol "XENIX", which alerts the C program that it runs under Xenix.

"date"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the date program. After Configure runs, the value is reset to a plain "date" and is not useful.

"db_hashtype"
From i_db.U:

This variable contains the type of the hash structure element in the <db.h> header file. In older versions of "DB", it was int, while in newer ones it is u_int32_t.

"db_prefixtype"
From i_db.U:

This variable contains the type of the prefix structure element in the <db.h> header file. In older versions of "DB", it was int, while in newer ones it is size_t.

"db_version_major"
From i_db.U:

This variable contains the major version number of Berkeley "DB" found in the <db.h> header file.

"db_version_minor"
From i_db.U:

This variable contains the minor version number of Berkeley "DB" found in the <db.h> header file. For "DB" version 1 this is always 0.

"db_version_patch"
From i_db.U:

This variable contains the patch version number of Berkeley "DB" found in the <db.h> header file. For "DB" version 1 this is always 0.

"default_inc_excludes_dot"
From defaultincdot.U:

When defined, remove the legacy . from @"INC"

"direntrytype"
From i_dirent.U:

This symbol is set to "struct direct" or "struct dirent" depending on whether dirent is available or not. You should use this pseudo type to portably declare your directory entries.

"dlext"
From dlext.U:

This variable contains the extension that is to be used for the dynamically loaded modules that perl generates.

"dlsrc"
From dlsrc.U:

This variable contains the name of the dynamic loading file that will be used with the package.

"doubleinfbytes"
From infnan.U:

This variable contains comma-separated list of hexadecimal bytes for the double precision infinity.

"doublekind"
From longdblfio.U:

This variable, if defined, encodes the type of a double: 1 = "IEEE" 754 32-bit little endian, 2 = "IEEE" 754 32-bit big endian, 3 = "IEEE" 754 64-bit little endian, 4 = "IEEE" 754 64-bit big endian, 5 = "IEEE" 754 128-bit little endian, 6 = "IEEE" 754 128-bit big endian, 7 = "IEEE" 754 64-bit mixed endian le-be, 8 = "IEEE" 754 64-bit mixed endian be-le, 9 = "VAX" 32bit little endian F float format 10 = "VAX" 64bit little endian D float format 11 = "VAX" 64bit little endian G float format 12 = "IBM" 32bit format 13 = "IBM" 64bit format 14 = Cray 64bit format -1 = unknown format.

"doublemantbits"
From mantbits.U:

This symbol, if defined, tells how many mantissa bits there are in double precision floating point format. Note that this is usually "DBL_MANT_DIG" minus one, since with the standard "IEEE" 754 formats "DBL_MANT_DIG" includes the implicit bit which doesn't really exist.

"doublenanbytes"
From infnan.U:

This variable contains comma-separated list of hexadecimal bytes for the double precision not-a-number.

"doublesize"
From doublesize.U:

This variable contains the value of the "DOUBLESIZE" symbol, which indicates to the C program how many bytes there are in a double.

"drand01"
From randfunc.U:

Indicates the macro to be used to generate normalized random numbers. Uses randfunc, often divided by (double) (((unsigned long) 1 << randbits)) in order to normalize the result. In C programs, the macro "Drand01" is mapped to drand01.

"drand48_r_proto"
From d_drand48_r.U:

This variable encodes the prototype of drand48_r. It is zero if d_drand48_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_drand48_r is defined.

"dtrace"
From usedtrace.U:

This variable holds the location of the dtrace executable.

"dtraceobject"
From dtraceobject.U:

Whether we need to build an object file with the dtrace tool.

"dtracexnolibs"
From dtraceobject.U:

Whether dtrace accepts -xnolibs. If available we call dtrace -h and dtrace -G with -xnolibs to allow dtrace to run in a jail on FreeBSD.

"dynamic_ext"
From Extensions.U:

This variable holds a list of "XS" extension files we want to link dynamically into the package. It is used by Makefile.

"eagain"
From nblock_io.U:

This variable bears the symbolic errno code set by read() when no data is present on the file and non-blocking I/O was enabled (otherwise, read() blocks naturally).

"ebcdic"
From ebcdic.U:

This variable conditionally defines "EBCDIC" if this system uses "EBCDIC" encoding.

"echo"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the echo program. After Configure runs, the value is reset to a plain "echo" and is not useful.

"egrep"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the egrep program. After Configure runs, the value is reset to a plain "egrep" and is not useful.

"emacs"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"endgrent_r_proto"
From d_endgrent_r.U:

This variable encodes the prototype of endgrent_r. It is zero if d_endgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_endgrent_r is defined.

"endhostent_r_proto"
From d_endhostent_r.U:

This variable encodes the prototype of endhostent_r. It is zero if d_endhostent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_endhostent_r is defined.

"endnetent_r_proto"
From d_endnetent_r.U:

This variable encodes the prototype of endnetent_r. It is zero if d_endnetent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_endnetent_r is defined.

"endprotoent_r_proto"
From d_endprotoent_r.U:

This variable encodes the prototype of endprotoent_r. It is zero if d_endprotoent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_endprotoent_r is defined.

"endpwent_r_proto"
From d_endpwent_r.U:

This variable encodes the prototype of endpwent_r. It is zero if d_endpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_endpwent_r is defined.

"endservent_r_proto"
From d_endservent_r.U:

This variable encodes the prototype of endservent_r. It is zero if d_endservent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_endservent_r is defined.

"eunicefix"
From Init.U:

When running under Eunice this variable contains a command which will convert a shell script to the proper form of text file for it to be executable by the shell. On other systems it is a no-op.

"exe_ext"
From Unix.U:

This is an old synonym for _exe.

"expr"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the expr program. After Configure runs, the value is reset to a plain "expr" and is not useful.

"extensions"
From Extensions.U:

This variable holds a list of all extension files (both "XS" and non-xs) installed with the package. It is propagated to Config.pm and is typically used to test whether a particular extension is available.

"extern_C"
From Csym.U:

"ANSI" C requires "extern" where C++ requires 'extern "C"'. This variable can be used in Configure to do the right thing.

"extras"
From Extras.U:

This variable holds a list of extra modules to install.

"fflushall"
From fflushall.U:

This symbol, if defined, tells that to flush all pending stdio output one must loop through all the stdio file handles stored in an array and fflush them. Note that if fflushNULL is defined, fflushall will not even be probed for and will be left undefined.

"fflushNULL"
From fflushall.U:

This symbol, if defined, tells that fflush("NULL") correctly flushes all pending stdio output without side effects. In particular, on some platforms calling fflush("NULL") *still* corrupts "STDIN" if it is a pipe.

"find"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"firstmakefile"
From Unix.U:

This variable defines the first file searched by make. On unix, it is makefile (then Makefile). On case-insensitive systems, it might be something else. This is only used to deal with convoluted make depend tricks.

"flex"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"fpossize"
From fpossize.U:

This variable contains the size of a fpostype in bytes.

"fpostype"
From fpostype.U:

This variable defines Fpos_t to be something like fpos_t, long, uint, or whatever type is used to declare file positions in libc.

"freetype"
From mallocsrc.U:

This variable contains the return type of free(). It is usually void, but occasionally int.

"from"
From Cross.U:

This variable contains the command used by Configure to copy files from the target host. Useful and available only during Perl build. The string ":" if not cross-compiling.

"full_ar"
From Loc_ar.U:

This variable contains the full pathname to "ar", whether or not the user has specified "portability". This is only used in the Makefile.SH.

"full_csh"
From d_csh.U:

This variable contains the full pathname to "csh", whether or not the user has specified "portability". This is only used in the compiled C program, and we assume that all systems which can share this executable will have the same full pathname to csh.

"full_sed"
From Loc_sed.U:

This variable contains the full pathname to "sed", whether or not the user has specified "portability". This is only used in the compiled C program, and we assume that all systems which can share this executable will have the same full pathname to sed.

"gccansipedantic"
From gccvers.U:

If "GNU" cc (gcc) is used, this variable will enable (if set) the -ansi and -pedantic ccflags for building core files (through cflags script). (See Porting/pumpkin.pod for full description).

"gccosandvers"
From gccvers.U:

If "GNU" cc (gcc) is used, this variable holds the operating system and version used to compile gcc. It is set to '' if not gcc, or if nothing useful can be parsed as the os version.

"gccversion"
From gccvers.U:

If "GNU" cc (gcc) is used, this variable holds 1 or 2 to indicate whether the compiler is version 1 or 2. This is used in setting some of the default cflags. It is set to '' if not gcc.

"getgrent_r_proto"
From d_getgrent_r.U:

This variable encodes the prototype of getgrent_r. It is zero if d_getgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getgrent_r is defined.

"getgrgid_r_proto"
From d_getgrgid_r.U:

This variable encodes the prototype of getgrgid_r. It is zero if d_getgrgid_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getgrgid_r is defined.

"getgrnam_r_proto"
From d_getgrnam_r.U:

This variable encodes the prototype of getgrnam_r. It is zero if d_getgrnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getgrnam_r is defined.

"gethostbyaddr_r_proto"
From d_gethostbyaddr_r.U:

This variable encodes the prototype of gethostbyaddr_r. It is zero if d_gethostbyaddr_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_gethostbyaddr_r is defined.

"gethostbyname_r_proto"
From d_gethostbyname_r.U:

This variable encodes the prototype of gethostbyname_r. It is zero if d_gethostbyname_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_gethostbyname_r is defined.

"gethostent_r_proto"
From d_gethostent_r.U:

This variable encodes the prototype of gethostent_r. It is zero if d_gethostent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_gethostent_r is defined.

"getlogin_r_proto"
From d_getlogin_r.U:

This variable encodes the prototype of getlogin_r. It is zero if d_getlogin_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getlogin_r is defined.

"getnetbyaddr_r_proto"
From d_getnetbyaddr_r.U:

This variable encodes the prototype of getnetbyaddr_r. It is zero if d_getnetbyaddr_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getnetbyaddr_r is defined.

"getnetbyname_r_proto"
From d_getnetbyname_r.U:

This variable encodes the prototype of getnetbyname_r. It is zero if d_getnetbyname_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getnetbyname_r is defined.

"getnetent_r_proto"
From d_getnetent_r.U:

This variable encodes the prototype of getnetent_r. It is zero if d_getnetent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getnetent_r is defined.

"getprotobyname_r_proto"
From d_getprotobyname_r.U:

This variable encodes the prototype of getprotobyname_r. It is zero if d_getprotobyname_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getprotobyname_r is defined.

"getprotobynumber_r_proto"
From d_getprotobynumber_r.U:

This variable encodes the prototype of getprotobynumber_r. It is zero if d_getprotobynumber_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getprotobynumber_r is defined.

"getprotoent_r_proto"
From d_getprotoent_r.U:

This variable encodes the prototype of getprotoent_r. It is zero if d_getprotoent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getprotoent_r is defined.

"getpwent_r_proto"
From d_getpwent_r.U:

This variable encodes the prototype of getpwent_r. It is zero if d_getpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getpwent_r is defined.

"getpwnam_r_proto"
From d_getpwnam_r.U:

This variable encodes the prototype of getpwnam_r. It is zero if d_getpwnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getpwnam_r is defined.

"getpwuid_r_proto"
From d_getpwuid_r.U:

This variable encodes the prototype of getpwuid_r. It is zero if d_getpwuid_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getpwuid_r is defined.

"getservbyname_r_proto"
From d_getservbyname_r.U:

This variable encodes the prototype of getservbyname_r. It is zero if d_getservbyname_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getservbyname_r is defined.

"getservbyport_r_proto"
From d_getservbyport_r.U:

This variable encodes the prototype of getservbyport_r. It is zero if d_getservbyport_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getservbyport_r is defined.

"getservent_r_proto"
From d_getservent_r.U:

This variable encodes the prototype of getservent_r. It is zero if d_getservent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getservent_r is defined.

"getspnam_r_proto"
From d_getspnam_r.U:

This variable encodes the prototype of getspnam_r. It is zero if d_getspnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_getspnam_r is defined.

"gidformat"
From gidf.U:

This variable contains the format string used for printing a Gid_t.

"gidsign"
From gidsign.U:

This variable contains the signedness of a gidtype. 1 for unsigned, -1 for signed.

"gidsize"
From gidsize.U:

This variable contains the size of a gidtype in bytes.

"gidtype"
From gidtype.U:

This variable defines Gid_t to be something like gid_t, int, ushort, or whatever type is used to declare the return type of getgid(). Typically, it is the type of group ids in the kernel.

"glibpth"
From libpth.U:

This variable holds the general path (space-separated) used to find libraries. It may contain directories that do not exist on this platform, libpth is the cleaned-up version.

"gmake"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the gmake program. After Configure runs, the value is reset to a plain "gmake" and is not useful.

"gmtime_r_proto"
From d_gmtime_r.U:

This variable encodes the prototype of gmtime_r. It is zero if d_gmtime_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_gmtime_r is defined.

"gnulibc_version"
From d_gnulibc.U:

This variable contains the version number of the "GNU" C library. It is usually something like 2.2.5. It is a plain '' if this is not the "GNU" C library, or if the version is unknown.

"grep"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the grep program. After Configure runs, the value is reset to a plain "grep" and is not useful.

"groupcat"
From nis.U:

This variable contains a command that produces the text of the /etc/group file. This is normally "cat /etc/group", but can be "ypcat group" when "NIS" is used. On some systems, such as os390, there may be no equivalent command, in which case this variable is unset.

"groupstype"
From groupstype.U:

This variable defines Groups_t to be something like gid_t, int, ushort, or whatever type is used for the second argument to getgroups() and setgroups(). Usually, this is the same as gidtype (gid_t), but sometimes it isn't.

"gzip"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the gzip program. After Configure runs, the value is reset to a plain "gzip" and is not useful.

"h_fcntl"
From h_fcntl.U:

This is variable gets set in various places to tell i_fcntl that <fcntl.h> should be included.

"h_sysfile"
From h_sysfile.U:

This is variable gets set in various places to tell i_sys_file that <sys/file.h> should be included.

"hint"
From Oldconfig.U:

Gives the type of hints used for previous answers. May be one of "default", "recommended" or "previous".

"hostcat"
From nis.U:

This variable contains a command that produces the text of the /etc/hosts file. This is normally "cat /etc/hosts", but can be "ypcat hosts" when "NIS" is used. On some systems, such as os390, there may be no equivalent command, in which case this variable is unset.

"hostgenerate"
From Cross.U:

This variable contains the path to a generate_uudmap binary that can be run on the host "OS" when cross-compiling. Useful and available only during Perl build. Empty string '' if not cross-compiling.

"hostosname"
From Cross.U:

This variable contains the original value of $^O for hostperl when cross-compiling. This is useful to pick the proper tools when running build code in the host. Empty string '' if not cross-compiling.

"hostperl"
From Cross.U:

This variable contains the path to a miniperl binary that can be run on the host "OS" when cross-compiling. Useful and available only during Perl build. Empty string '' if not cross-compiling.

"html1dir"
From html1dir.U:

This variable contains the name of the directory in which html source pages are to be put. This directory is for pages that describe whole programs, not libraries or modules. It is intended to correspond roughly to section 1 of the Unix manuals.

"html1direxp"
From html1dir.U:

This variable is the same as the html1dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

"html3dir"
From html3dir.U:

This variable contains the name of the directory in which html source pages are to be put. This directory is for pages that describe libraries or modules. It is intended to correspond roughly to section 3 of the Unix manuals.

"html3direxp"
From html3dir.U:

This variable is the same as the html3dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

"i16size"
From perlxv.U:

This variable is the size of an I16 in bytes.

"i16type"
From perlxv.U:

This variable contains the C type used for Perl's I16.

"i32size"
From perlxv.U:

This variable is the size of an I32 in bytes.

"i32type"
From perlxv.U:

This variable contains the C type used for Perl's I32.

"i64size"
From perlxv.U:

This variable is the size of an I64 in bytes.

"i64type"
From perlxv.U:

This variable contains the C type used for Perl's I64.

"i8size"
From perlxv.U:

This variable is the size of an I8 in bytes.

"i8type"
From perlxv.U:

This variable contains the C type used for Perl's I8.

"i_arpainet"
From i_arpainet.U:

This variable conditionally defines the "I_ARPA_INET" symbol, and indicates whether a C program should include <arpa/inet.h>.

"i_bfd"
From i_bfd.U:

This variable conditionally defines the "I_BFD" symbol, and indicates whether a C program can include <bfd.h>.

"i_bsdioctl"
From i_sysioctl.U:

This variable conditionally defines the "I_SYS_BSDIOCTL" symbol, which indicates to the C program that <sys/bsdioctl.h> exists and should be included.

"i_crypt"
From i_crypt.U:

This variable conditionally defines the "I_CRYPT" symbol, and indicates whether a C program should include <crypt.h>.

"i_db"
From i_db.U:

This variable conditionally defines the "I_DB" symbol, and indicates whether a C program may include Berkeley's "DB" include file <db.h>.

"i_dbm"
From i_dbm.U:

This variable conditionally defines the "I_DBM" symbol, which indicates to the C program that <dbm.h> exists and should be included.

"i_dirent"
From i_dirent.U:

This variable conditionally defines "I_DIRENT", which indicates to the C program that it should include <dirent.h>.

"i_dlfcn"
From i_dlfcn.U:

This variable conditionally defines the "I_DLFCN" symbol, which indicates to the C program that <dlfcn.h> exists and should be included.

"i_execinfo"
From i_execinfo.U:

This variable conditionally defines the "I_EXECINFO" symbol, and indicates whether a C program may include <execinfo.h>, for backtrace() support.

"i_fcntl"
From i_fcntl.U:

This variable controls the value of "I_FCNTL" (which tells the C program to include <fcntl.h>).

"i_fenv"
From i_fenv.U:

This variable conditionally defines the "I_FENV" symbol, which indicates to the C program that <fenv.h> exists and should be included.

"i_fp"
From i_fp.U:

This variable conditionally defines the "I_FP" symbol, and indicates whether a C program should include <fp.h>.

"i_fp_class"
From i_fp_class.U:

This variable conditionally defines the "I_FP_CLASS" symbol, and indicates whether a C program should include <fp_class.h>.

"i_gdbm"
From i_gdbm.U:

This variable conditionally defines the "I_GDBM" symbol, which indicates to the C program that <gdbm.h> exists and should be included.

"i_gdbm_ndbm"
From i_ndbm.U:

This variable conditionally defines the "I_GDBM_NDBM" symbol, which indicates to the C program that <gdbm-ndbm.h> exists and should be included. This is the location of the ndbm.h compatibility file in Debian 4.0.

"i_gdbmndbm"
From i_ndbm.U:

This variable conditionally defines the "I_GDBMNDBM" symbol, which indicates to the C program that <gdbm/ndbm.h> exists and should be included. This was the location of the ndbm.h compatibility file in RedHat 7.1.

"i_grp"
From i_grp.U:

This variable conditionally defines the "I_GRP" symbol, and indicates whether a C program should include <grp.h>.

"i_ieeefp"
From i_ieeefp.U:

This variable conditionally defines the "I_IEEEFP" symbol, and indicates whether a C program should include <ieeefp.h>.

"i_inttypes"
From i_inttypes.U:

This variable conditionally defines the "I_INTTYPES" symbol, and indicates whether a C program should include <inttypes.h>.

"i_langinfo"
From i_langinfo.U:

This variable conditionally defines the "I_LANGINFO" symbol, and indicates whether a C program should include <langinfo.h>.

"i_libutil"
From i_libutil.U:

This variable conditionally defines the "I_LIBUTIL" symbol, and indicates whether a C program should include <libutil.h>.

"i_locale"
From i_locale.U:

This variable conditionally defines the "I_LOCALE" symbol, and indicates whether a C program should include <locale.h>.

"i_machcthr"
From i_machcthr.U:

This variable conditionally defines the "I_MACH_CTHREADS" symbol, and indicates whether a C program should include <mach/cthreads.h>.

"i_malloc"
From i_malloc.U:

This variable conditionally defines the "I_MALLOC" symbol, and indicates whether a C program should include <malloc.h>.

"i_mallocmalloc"
From i_mallocmalloc.U:

This variable conditionally defines the "I_MALLOCMALLOC" symbol, and indicates whether a C program should include <malloc/malloc.h>.

"i_mntent"
From i_mntent.U:

This variable conditionally defines the "I_MNTENT" symbol, and indicates whether a C program should include <mntent.h>.

"i_ndbm"
From i_ndbm.U:

This variable conditionally defines the "I_NDBM" symbol, which indicates to the C program that <ndbm.h> exists and should be included.

"i_netdb"
From i_netdb.U:

This variable conditionally defines the "I_NETDB" symbol, and indicates whether a C program should include <netdb.h>.

"i_neterrno"
From i_neterrno.U:

This variable conditionally defines the "I_NET_ERRNO" symbol, which indicates to the C program that <net/errno.h> exists and should be included.

"i_netinettcp"
From i_netinettcp.U:

This variable conditionally defines the "I_NETINET_TCP" symbol, and indicates whether a C program should include <netinet/tcp.h>.

"i_niin"
From i_niin.U:

This variable conditionally defines "I_NETINET_IN", which indicates to the C program that it should include <netinet/in.h>. Otherwise, you may try <sys/in.h>.

"i_poll"
From i_poll.U:

This variable conditionally defines the "I_POLL" symbol, and indicates whether a C program should include <poll.h>.

"i_prot"
From i_prot.U:

This variable conditionally defines the "I_PROT" symbol, and indicates whether a C program should include <prot.h>.

"i_pthread"
From i_pthread.U:

This variable conditionally defines the "I_PTHREAD" symbol, and indicates whether a C program should include <pthread.h>.

"i_pwd"
From i_pwd.U:

This variable conditionally defines "I_PWD", which indicates to the C program that it should include <pwd.h>.

"i_quadmath"
From i_quadmath.U:

This variable conditionally defines "I_QUADMATH", which indicates to the C program that it should include <quadmath.h>.

"i_rpcsvcdbm"
From i_dbm.U:

This variable conditionally defines the "I_RPCSVC_DBM" symbol, which indicates to the C program that <rpcsvc/dbm.h> exists and should be included. Some System V systems might need this instead of <dbm.h>.

"i_sgtty"
From i_termio.U:

This variable conditionally defines the "I_SGTTY" symbol, which indicates to the C program that it should include <sgtty.h> rather than <termio.h>.

"i_shadow"
From i_shadow.U:

This variable conditionally defines the "I_SHADOW" symbol, and indicates whether a C program should include <shadow.h>.

"i_socks"
From i_socks.U:

This variable conditionally defines the "I_SOCKS" symbol, and indicates whether a C program should include <socks.h>.

"i_stdbool"
From i_stdbool.U:

This variable conditionally defines the "I_STDBOOL" symbol, which indicates to the C program that <stdbool.h> exists and should be included.

"i_stdint"
From i_stdint.U:

This variable conditionally defines the "I_STDINT" symbol, which indicates to the C program that <stdint.h> exists and should be included.

"i_stdlib"
From i_stdlib.U:

This variable unconditionally defines the "I_STDLIB" symbol.

"i_sunmath"
From i_sunmath.U:

This variable conditionally defines the "I_SUNMATH" symbol, and indicates whether a C program should include <sunmath.h>.

"i_sysaccess"
From i_sysaccess.U:

This variable conditionally defines the "I_SYS_ACCESS" symbol, and indicates whether a C program should include <sys/access.h>.

"i_sysdir"
From i_sysdir.U:

This variable conditionally defines the "I_SYS_DIR" symbol, and indicates whether a C program should include <sys/dir.h>.

"i_sysfile"
From i_sysfile.U:

This variable conditionally defines the "I_SYS_FILE" symbol, and indicates whether a C program should include <sys/file.h> to get "R_OK" and friends.

"i_sysfilio"
From i_sysioctl.U:

This variable conditionally defines the "I_SYS_FILIO" symbol, which indicates to the C program that <sys/filio.h> exists and should be included in preference to <sys/ioctl.h>.

"i_sysin"
From i_niin.U:

This variable conditionally defines "I_SYS_IN", which indicates to the C program that it should include <sys/in.h> instead of <netinet/in.h>.

"i_sysioctl"
From i_sysioctl.U:

This variable conditionally defines the "I_SYS_IOCTL" symbol, which indicates to the C program that <sys/ioctl.h> exists and should be included.

"i_syslog"
From i_syslog.U:

This variable conditionally defines the "I_SYSLOG" symbol, and indicates whether a C program should include <syslog.h>.

"i_sysmman"
From i_sysmman.U:

This variable conditionally defines the "I_SYS_MMAN" symbol, and indicates whether a C program should include <sys/mman.h>.

"i_sysmode"
From i_sysmode.U:

This variable conditionally defines the "I_SYSMODE" symbol, and indicates whether a C program should include <sys/mode.h>.

"i_sysmount"
From i_sysmount.U:

This variable conditionally defines the "I_SYSMOUNT" symbol, and indicates whether a C program should include <sys/mount.h>.

"i_sysndir"
From i_sysndir.U:

This variable conditionally defines the "I_SYS_NDIR" symbol, and indicates whether a C program should include <sys/ndir.h>.

"i_sysparam"
From i_sysparam.U:

This variable conditionally defines the "I_SYS_PARAM" symbol, and indicates whether a C program should include <sys/param.h>.

"i_syspoll"
From i_syspoll.U:

This variable conditionally defines the "I_SYS_POLL" symbol, which indicates to the C program that it should include <sys/poll.h>.

"i_sysresrc"
From i_sysresrc.U:

This variable conditionally defines the "I_SYS_RESOURCE" symbol, and indicates whether a C program should include <sys/resource.h>.

"i_syssecrt"
From i_syssecrt.U:

This variable conditionally defines the "I_SYS_SECURITY" symbol, and indicates whether a C program should include <sys/security.h>.

"i_sysselct"
From i_sysselct.U:

This variable conditionally defines "I_SYS_SELECT", which indicates to the C program that it should include <sys/select.h> in order to get the definition of struct timeval.

"i_syssockio"
From i_sysioctl.U:

This variable conditionally defines "I_SYS_SOCKIO" to indicate to the C program that socket ioctl codes may be found in <sys/sockio.h> instead of <sys/ioctl.h>.

"i_sysstat"
From i_sysstat.U:

This variable conditionally defines the "I_SYS_STAT" symbol, and indicates whether a C program should include <sys/stat.h>.

"i_sysstatfs"
From i_sysstatfs.U:

This variable conditionally defines the "I_SYSSTATFS" symbol, and indicates whether a C program should include <sys/statfs.h>.

"i_sysstatvfs"
From i_sysstatvfs.U:

This variable conditionally defines the "I_SYSSTATVFS" symbol, and indicates whether a C program should include <sys/statvfs.h>.

"i_systime"
From i_time.U:

This variable conditionally defines "I_SYS_TIME", which indicates to the C program that it should include <sys/time.h>.

"i_systimek"
From i_time.U:

This variable conditionally defines "I_SYS_TIME_KERNEL", which indicates to the C program that it should include <sys/time.h> with "KERNEL" defined.

"i_systimes"
From i_systimes.U:

This variable conditionally defines the "I_SYS_TIMES" symbol, and indicates whether a C program should include <sys/times.h>.

"i_systypes"
From i_systypes.U:

This variable conditionally defines the "I_SYS_TYPES" symbol, and indicates whether a C program should include <sys/types.h>.

"i_sysuio"
From i_sysuio.U:

This variable conditionally defines the "I_SYSUIO" symbol, and indicates whether a C program should include <sys/uio.h>.

"i_sysun"
From i_sysun.U:

This variable conditionally defines "I_SYS_UN", which indicates to the C program that it should include <sys/un.h> to get "UNIX" domain socket definitions.

"i_sysutsname"
From i_sysutsname.U:

This variable conditionally defines the "I_SYSUTSNAME" symbol, and indicates whether a C program should include <sys/utsname.h>.

"i_sysvfs"
From i_sysvfs.U:

This variable conditionally defines the "I_SYSVFS" symbol, and indicates whether a C program should include <sys/vfs.h>.

"i_syswait"
From i_syswait.U:

This variable conditionally defines "I_SYS_WAIT", which indicates to the C program that it should include <sys/wait.h>.

"i_termio"
From i_termio.U:

This variable conditionally defines the "I_TERMIO" symbol, which indicates to the C program that it should include <termio.h> rather than <sgtty.h>.

"i_termios"
From i_termio.U:

This variable conditionally defines the "I_TERMIOS" symbol, which indicates to the C program that the "POSIX" <termios.h> file is to be included.

"i_time"
From i_time.U:

This variable unconditionally defines "I_TIME", which indicates to the C program that it should include <time.h>.

"i_unistd"
From i_unistd.U:

This variable conditionally defines the "I_UNISTD" symbol, and indicates whether a C program should include <unistd.h>.

"i_ustat"
From i_ustat.U:

This variable conditionally defines the "I_USTAT" symbol, and indicates whether a C program should include <ustat.h>.

"i_utime"
From i_utime.U:

This variable conditionally defines the "I_UTIME" symbol, and indicates whether a C program should include <utime.h>.

"i_vfork"
From i_vfork.U:

This variable conditionally defines the "I_VFORK" symbol, and indicates whether a C program should include vfork.h.

"i_wchar"
From i_wchar.U:

This variable conditionally defines the "I_WCHAR" symbol, that indicates whether a C program may include <wchar.h>.

"i_wctype"
From i_wctype.U:

This variable conditionally defines the "I_WCTYPE" symbol, that indicates whether a C program may include <wctype.h>.

"i_xlocale"
From d_newlocale.U:

This symbol, if defined, indicates to the C program that it should include <xlocale.h> to get uselocale() and its friends

"ignore_versioned_solibs"
From libs.U:

This variable should be non-empty if non-versioned shared libraries (libfoo.so.x.y) are to be ignored (because they cannot be linked against).

"inc_version_list"
From inc_version_list.U:

This variable specifies the list of subdirectories in over which perl.c:incpush() and lib/lib.pm will automatically search when adding directories to @"INC". The elements in the list are separated by spaces. This is only useful if you have a perl library directory tree structured like the default one. See "INSTALL" for how this works. The versioned site_perl directory was introduced in 5.005, so that is the lowest possible value.

This list includes architecture-dependent directories back to version $api_versionstring (e.g. 5.5.640) and architecture-independent directories all the way back to 5.005.

"inc_version_list_init"
From inc_version_list.U:

This variable holds the same list as inc_version_list, but each item is enclosed in double quotes and separated by commas, suitable for use in the "PERL_INC_VERSION_LIST" initialization.

"incpath"
From usrinc.U:

This variable must precede the normal include path to get the right one, as in $incpath/usr/include or $incpath/usr/lib. Value can be "" or /bsd43 on mips.

"incpth"
From libpth.U:

This variable must precede the normal include path to get the right one, as in $incpath/usr/include or $incpath/usr/lib. Value can be "" or /bsd43 on mips.

"inews"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"initialinstalllocation"
From bin.U:

When userelocatableinc is true, this variable holds the location that make install should copy the perl binary to, with all the run-time relocatable paths calculated from this at install time. When used, it is initialized to the original value of binexp, and then binexp is set to .../, as the other binaries are found relative to the perl binary.

"installarchlib"
From archlib.U:

This variable is really the same as archlibexp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installbin"
From bin.U:

This variable is the same as binexp unless "AFS" is running in which case the user is explicitly prompted for it. This variable should always be used in your makefiles for maximum portability.

"installhtml1dir"
From html1dir.U:

This variable is really the same as html1direxp, unless you are using a different installprefix. For extra portability, you should only use this variable within your makefiles.

"installhtml3dir"
From html3dir.U:

This variable is really the same as html3direxp, unless you are using a different installprefix. For extra portability, you should only use this variable within your makefiles.

"installman1dir"
From man1dir.U:

This variable is really the same as man1direxp, unless you are using "AFS" in which case it points to the read/write location whereas man1direxp only points to the read-only access location. For extra portability, you should only use this variable within your makefiles.

"installman3dir"
From man3dir.U:

This variable is really the same as man3direxp, unless you are using "AFS" in which case it points to the read/write location whereas man3direxp only points to the read-only access location. For extra portability, you should only use this variable within your makefiles.

"installprefix"
From installprefix.U:

This variable holds the name of the directory below which "make install" will install the package. For most users, this is the same as prefix. However, it is useful for installing the software into a different (usually temporary) location after which it can be bundled up and moved somehow to the final location specified by prefix.

"installprefixexp"
From installprefix.U:

This variable holds the full absolute path of installprefix with all ~-expansion done.

"installprivlib"
From privlib.U:

This variable is really the same as privlibexp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installscript"
From scriptdir.U:

This variable is usually the same as scriptdirexp, unless you are on a system running "AFS", in which case they may differ slightly. You should always use this variable within your makefiles for portability.

"installsitearch"
From sitearch.U:

This variable is really the same as sitearchexp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installsitebin"
From sitebin.U:

This variable is usually the same as sitebinexp, unless you are on a system running "AFS", in which case they may differ slightly. You should always use this variable within your makefiles for portability.

"installsitehtml1dir"
From sitehtml1dir.U:

This variable is really the same as sitehtml1direxp, unless you are using "AFS" in which case it points to the read/write location whereas html1direxp only points to the read-only access location. For extra portability, you should only use this variable within your makefiles.

"installsitehtml3dir"
From sitehtml3dir.U:

This variable is really the same as sitehtml3direxp, unless you are using "AFS" in which case it points to the read/write location whereas html3direxp only points to the read-only access location. For extra portability, you should only use this variable within your makefiles.

"installsitelib"
From sitelib.U:

This variable is really the same as sitelibexp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installsiteman1dir"
From siteman1dir.U:

This variable is really the same as siteman1direxp, unless you are using "AFS" in which case it points to the read/write location whereas man1direxp only points to the read-only access location. For extra portability, you should only use this variable within your makefiles.

"installsiteman3dir"
From siteman3dir.U:

This variable is really the same as siteman3direxp, unless you are using "AFS" in which case it points to the read/write location whereas man3direxp only points to the read-only access location. For extra portability, you should only use this variable within your makefiles.

"installsitescript"
From sitescript.U:

This variable is usually the same as sitescriptexp, unless you are on a system running "AFS", in which case they may differ slightly. You should always use this variable within your makefiles for portability.

"installstyle"
From installstyle.U:

This variable describes the "style" of the perl installation. This is intended to be useful for tools that need to manipulate entire perl distributions. Perl itself doesn't use this to find its libraries -- the library directories are stored directly in Config.pm. Currently, there are only two styles: "lib" and lib/perl5. The default library locations (e.g. privlib, sitelib) are either $prefix/lib or $prefix/lib/perl5. The former is useful if $prefix is a directory dedicated to perl (e.g. /opt/perl), while the latter is useful if $prefix is shared by many packages, e.g. if $prefix=/usr/local.

Unfortunately, while this "style" variable is used to set defaults for all three directory hierarchies (core, vendor, and site), there is no guarantee that the same style is actually appropriate for all those directories. For example, $prefix might be /opt/perl, but $siteprefix might be /usr/local. (Perhaps, in retrospect, the "lib" style should never have been supported, but it did seem like a nice idea at the time.)

The situation is even less clear for tools such as MakeMaker that can be used to install additional modules into non-standard places. For example, if a user intends to install a module into a private directory (perhaps by setting "PREFIX" on the Makefile.PL command line), then there is no reason to assume that the Configure-time $installstyle setting will be relevant for that "PREFIX".

This may later be extended to include other information, so be careful with pattern-matching on the results.

For compatibility with perl5.005 and earlier, the default setting is based on whether or not $prefix contains the string "perl".

"installusrbinperl"
From instubperl.U:

This variable tells whether Perl should be installed also as /usr/bin/perl in addition to $installbin/perl

"installvendorarch"
From vendorarch.U:

This variable is really the same as vendorarchexp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installvendorbin"
From vendorbin.U:

This variable is really the same as vendorbinexp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installvendorhtml1dir"
From vendorhtml1dir.U:

This variable is really the same as vendorhtml1direxp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installvendorhtml3dir"
From vendorhtml3dir.U:

This variable is really the same as vendorhtml3direxp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installvendorlib"
From vendorlib.U:

This variable is really the same as vendorlibexp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installvendorman1dir"
From vendorman1dir.U:

This variable is really the same as vendorman1direxp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installvendorman3dir"
From vendorman3dir.U:

This variable is really the same as vendorman3direxp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"installvendorscript"
From vendorscript.U:

This variable is really the same as vendorscriptexp but may differ on those systems using "AFS". For extra portability, only this variable should be used in makefiles.

"intsize"
From intsize.U:

This variable contains the value of the "INTSIZE" symbol, which indicates to the C program how many bytes there are in an int.

"issymlink"
From issymlink.U:

This variable holds the test command to test for a symbolic link (if they are supported). Typical values include "test -h" and "test -L".

"ivdformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "IV" as a signed decimal integer.

"ivsize"
From perlxv.U:

This variable is the size of an "IV" in bytes.

"ivtype"
From perlxv.U:

This variable contains the C type used for Perl's "IV".

"known_extensions"
From Extensions.U:

This variable holds a list of all extensions (both "XS" and non-xs) included in the package source distribution. This information is only really of use during the Perl build, as the list makes no distinction between extensions which were build and installed, and those which where not. See "extensions" for the list of extensions actually built and available.

"ksh"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"ld"
From dlsrc.U:

This variable indicates the program to be used to link libraries for dynamic loading. On some systems, it is "ld". On "ELF" systems, it should be $cc. Mostly, we'll try to respect the hint file setting.

"ld_can_script"
From dlsrc.U:

This variable shows if the loader accepts scripts in the form of -Wl,--version-script=ld.script. This is currently only supported for "GNU" ld on "ELF" in dynamic loading builds.

"lddlflags"
From dlsrc.U:

This variable contains any special flags that might need to be passed to $ld to create a shared library suitable for dynamic loading. It is up to the makefile to use it. For hpux, it should be "-b". For sunos 4.1, it is empty.

"ldflags"
From ccflags.U:

This variable contains any additional C loader flags desired by the user. It is up to the Makefile to use this.

"ldflags_uselargefiles"
From uselfs.U:

This variable contains the loader flags needed by large file builds and added to ldflags by hints files.

"ldlibpthname"
From libperl.U:

This variable holds the name of the shared library search path, often "LD_LIBRARY_PATH". To get an empty string, the hints file must set this to "none".

"less"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the less program. After Configure runs, the value is reset to a plain "less" and is not useful.

"lib_ext"
From Unix.U:

This is an old synonym for _a.

"libc"
From libc.U:

This variable contains the location of the C library.

"libperl"
From libperl.U:

The perl executable is obtained by linking perlmain.c with libperl, any static extensions (usually just DynaLoader), and any other libraries needed on this system. libperl is usually libperl.a, but can also be libperl.so.xxx if the user wishes to build a perl executable with a shared library.

"libpth"
From libpth.U:

This variable holds the general path (space-separated) used to find libraries. It is intended to be used by other units.

"libs"
From libs.U:

This variable holds the additional libraries we want to use. It is up to the Makefile to deal with it. The list can be empty.

"libsdirs"
From libs.U:

This variable holds the directory names aka dirnames of the libraries we found and accepted, duplicates are removed.

"libsfiles"
From libs.U:

This variable holds the filenames aka basenames of the libraries we found and accepted.

"libsfound"
From libs.U:

This variable holds the full pathnames of the libraries we found and accepted.

"libspath"
From libs.U:

This variable holds the directory names probed for libraries.

"libswanted"
From Myinit.U:

This variable holds a list of all the libraries we want to search. The order is chosen to pick up the c library ahead of ucb or bsd libraries for SVR4.

"libswanted_uselargefiles"
From uselfs.U:

This variable contains the libraries needed by large file builds and added to ldflags by hints files. It is a space separated list of the library names without the "lib" prefix or any suffix, just like libswanted..

"line"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"lint"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"lkflags"
From ccflags.U:

This variable contains any additional C partial linker flags desired by the user. It is up to the Makefile to use this.

"ln"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the ln program. After Configure runs, the value is reset to a plain "ln" and is not useful.

"lns"
From lns.U:

This variable holds the name of the command to make symbolic links (if they are supported). It can be used in the Makefile. It is either "ln -s" or "ln"

"localtime_r_proto"
From d_localtime_r.U:

This variable encodes the prototype of localtime_r. It is zero if d_localtime_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_localtime_r is defined.

"locincpth"
From ccflags.U:

This variable contains a list of additional directories to be searched by the compiler. The appropriate "-I" directives will be added to ccflags. This is intended to simplify setting local directories from the Configure command line. It's not much, but it parallels the loclibpth stuff in libpth.U.

"loclibpth"
From libpth.U:

This variable holds the paths (space-separated) used to find local libraries. It is prepended to libpth, and is intended to be easily set from the command line.

"longdblinfbytes"
From infnan.U:

This variable contains comma-separated list of hexadecimal bytes for the long double precision infinity.

"longdblkind"
From d_longdbl.U:

This variable, if defined, encodes the type of a long double: 0 = double, 1 = "IEEE" 754 128-bit little endian, 2 = "IEEE" 754 128-bit big endian, 3 = x86 80-bit little endian, 4 = x86 80-bit big endian, 5 = double-double 128-bit little endian, 6 = double-double 128-bit big endian, 7 = 128-bit mixed-endian double-double (64-bit LEs in "BE"), 8 = 128-bit mixed-endian double-double (64-bit BEs in "LE"), 9 = 128-bit "PDP"-style mixed-endian long doubles, -1 = unknown format.

"longdblmantbits"
From mantbits.U:

This symbol, if defined, tells how many mantissa bits there are in long double precision floating point format. Note that this can be "LDBL_MANT_DIG" minus one, since "LDBL_MANT_DIG" can include the "IEEE" 754 implicit bit. The common x86-style 80-bit long double does not have an implicit bit.

"longdblnanbytes"
From infnan.U:

This variable contains comma-separated list of hexadecimal bytes for the long double precision not-a-number.

"longdblsize"
From d_longdbl.U:

This variable contains the value of the "LONG_DOUBLESIZE" symbol, which indicates to the C program how many bytes there are in a long double, if this system supports long doubles. Note that this is sizeof(long double), which may include unused bytes.

"longlongsize"
From d_longlong.U:

This variable contains the value of the "LONGLONGSIZE" symbol, which indicates to the C program how many bytes there are in a long long, if this system supports long long.

"longsize"
From intsize.U:

This variable contains the value of the "LONGSIZE" symbol, which indicates to the C program how many bytes there are in a long.

"lp"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"lpr"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"ls"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the ls program. After Configure runs, the value is reset to a plain "ls" and is not useful.

"lseeksize"
From lseektype.U:

This variable defines lseektype to be something like off_t, long, or whatever type is used to declare lseek offset's type in the kernel (which also appears to be lseek's return type).

"lseektype"
From lseektype.U:

This variable defines lseektype to be something like off_t, long, or whatever type is used to declare lseek offset's type in the kernel (which also appears to be lseek's return type).

"mail"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"mailx"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"make"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the make program. After Configure runs, the value is reset to a plain "make" and is not useful.

"make_set_make"
From make.U:

Some versions of "make" set the variable "MAKE". Others do not. This variable contains the string to be included in Makefile.SH so that "MAKE" is set if needed, and not if not needed. Possible values are:

make_set_make="#" # If your make program handles this for you,

make_set_make="MAKE=$make" # if it doesn't.

This uses a comment character so that we can distinguish a "set" value (from a previous config.sh or Configure "-D" option) from an uncomputed value.

"mallocobj"
From mallocsrc.U:

This variable contains the name of the malloc.o that this package generates, if that malloc.o is preferred over the system malloc. Otherwise the value is null. This variable is intended for generating Makefiles. See mallocsrc.

"mallocsrc"
From mallocsrc.U:

This variable contains the name of the malloc.c that comes with the package, if that malloc.c is preferred over the system malloc. Otherwise the value is null. This variable is intended for generating Makefiles.

"malloctype"
From mallocsrc.U:

This variable contains the kind of ptr returned by malloc and realloc.

"man1dir"
From man1dir.U:

This variable contains the name of the directory in which manual source pages are to be put. It is the responsibility of the Makefile.SH to get the value of this into the proper command. You must be prepared to do the ~name expansion yourself.

"man1direxp"
From man1dir.U:

This variable is the same as the man1dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

"man1ext"
From man1dir.U:

This variable contains the extension that the manual page should have: one of "n", "l", or 1. The Makefile must supply the .. See man1dir.

"man3dir"
From man3dir.U:

This variable contains the name of the directory in which manual source pages are to be put. It is the responsibility of the Makefile.SH to get the value of this into the proper command. You must be prepared to do the ~name expansion yourself.

"man3direxp"
From man3dir.U:

This variable is the same as the man3dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

"man3ext"
From man3dir.U:

This variable contains the extension that the manual page should have: one of "n", "l", or 3. The Makefile must supply the .. See man3dir.

"mips_type"
From usrinc.U:

This variable holds the environment type for the mips system. Possible values are "BSD 4.3" and "System V".

"mistrustnm"
From Csym.U:

This variable can be used to establish a fallthrough for the cases where nm fails to find a symbol. If usenm is false or usenm is true and mistrustnm is false, this variable has no effect. If usenm is true and mistrustnm is "compile", a test program will be compiled to try to find any symbol that can't be located via nm lookup. If mistrustnm is "run", the test program will be run as well as being compiled.

"mkdir"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the mkdir program. After Configure runs, the value is reset to a plain "mkdir" and is not useful.

"mmaptype"
From d_mmap.U:

This symbol contains the type of pointer returned by mmap() (and simultaneously the type of the first argument). It can be "void *" or "caddr_t".

"modetype"
From modetype.U:

This variable defines modetype to be something like mode_t, int, unsigned short, or whatever type is used to declare file modes for system calls.

"more"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the more program. After Configure runs, the value is reset to a plain "more" and is not useful.

"multiarch"
From multiarch.U:

This variable conditionally defines the "MULTIARCH" symbol which signifies the presence of multiplatform files. This is normally set by hints files.

"mv"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"myarchname"
From archname.U:

This variable holds the architecture name computed by Configure in a previous run. It is not intended to be perused by any user and should never be set in a hint file.

"mydomain"
From myhostname.U:

This variable contains the eventual value of the "MYDOMAIN" symbol, which is the domain of the host the program is going to run on. The domain must be appended to myhostname to form a complete host name. The dot comes with mydomain, and need not be supplied by the program.

"myhostname"
From myhostname.U:

This variable contains the eventual value of the "MYHOSTNAME" symbol, which is the name of the host the program is going to run on. The domain is not kept with hostname, but must be gotten from mydomain. The dot comes with mydomain, and need not be supplied by the program.

"myuname"
From Oldconfig.U:

The output of "uname -a" if available, otherwise the hostname. The whole thing is then lower-cased and slashes and single quotes are removed.

"n"
From n.U:

This variable contains the "-n" flag if that is what causes the echo command to suppress newline. Otherwise it is null. Correct usage is $echo $n "prompt for a question: $c".

"need_va_copy"
From need_va_copy.U:

This symbol, if defined, indicates that the system stores the variable argument list datatype, va_list, in a format that cannot be copied by simple assignment, so that some other means must be used when copying is required. As such systems vary in their provision (or non-provision) of copying mechanisms, handy.h defines a platform- "independent" macro, Perl_va_copy(src, dst), to do the job.

"netdb_hlen_type"
From netdbtype.U:

This variable holds the type used for the 2nd argument to gethostbyaddr(). Usually, this is int or size_t or unsigned. This is only useful if you have gethostbyaddr(), naturally.

"netdb_host_type"
From netdbtype.U:

This variable holds the type used for the 1st argument to gethostbyaddr(). Usually, this is char * or void *, possibly with or without a const prefix. This is only useful if you have gethostbyaddr(), naturally.

"netdb_name_type"
From netdbtype.U:

This variable holds the type used for the argument to gethostbyname(). Usually, this is char * or const char *. This is only useful if you have gethostbyname(), naturally.

"netdb_net_type"
From netdbtype.U:

This variable holds the type used for the 1st argument to getnetbyaddr(). Usually, this is int or long. This is only useful if you have getnetbyaddr(), naturally.

"nm"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the nm program. After Configure runs, the value is reset to a plain "nm" and is not useful.

"nm_opt"
From usenm.U:

This variable holds the options that may be necessary for nm.

"nm_so_opt"
From usenm.U:

This variable holds the options that may be necessary for nm to work on a shared library but that can not be used on an archive library. Currently, this is only used by Linux, where nm --dynamic is *required* to get symbols from an "ELF" library which has been stripped, but nm --dynamic is *fatal* on an archive library. Maybe Linux should just always set usenm=false.

"nonxs_ext"
From Extensions.U:

This variable holds a list of all non-xs extensions built and installed by the package. By default, all non-xs extensions distributed will be built, with the exception of platform-specific extensions (currently only one "VMS" specific extension).

"nroff"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the nroff program. After Configure runs, the value is reset to a plain "nroff" and is not useful.

"nv_overflows_integers_at"
From perlxv.U:

This variable gives the largest integer value that NVs can hold as a constant floating point expression. If it could not be determined, it holds the value 0.

"nv_preserves_uv_bits"
From perlxv.U:

This variable indicates how many of bits type uvtype a variable nvtype can preserve.

"nveformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "NV" using %e-ish floating point format.

"nvEUformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "NV" using %E-ish floating point format.

"nvfformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "NV" using %f-ish floating point format.

"nvFUformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "NV" using %F-ish floating point format.

"nvgformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "NV" using %g-ish floating point format.

"nvGUformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "NV" using %G-ish floating point format.

"nvmantbits"
From mantbits.U:

This variable tells how many bits the mantissa of a Perl "NV" has, not including the possible implicit bit.

"nvsize"
From perlxv.U:

This variable is the size of a Perl "NV" in bytes. Note that some floating point formats have unused bytes.

"nvtype"
From perlxv.U:

This variable contains the C type used for Perl's "NV".

"o_nonblock"
From nblock_io.U:

This variable bears the symbol value to be used during open() or fcntl() to turn on non-blocking I/O for a file descriptor. If you wish to switch between blocking and non-blocking, you may try ioctl("FIOSNBIO") instead, but that is only supported by some devices.

"obj_ext"
From Unix.U:

This is an old synonym for _o.

"old_pthread_create_joinable"
From d_pthrattrj.U:

This variable defines the constant to use for creating joinable (aka undetached) pthreads. Unused if pthread.h defines "PTHREAD_CREATE_JOINABLE". If used, possible values are "PTHREAD_CREATE_UNDETACHED" and "__UNDETACHED".

"optimize"
From ccflags.U:

This variable contains any optimizer/debugger flag that should be used. It is up to the Makefile to use it.

"orderlib"
From orderlib.U:

This variable is "true" if the components of libraries must be ordered (with `lorder $* | tsort`) before placing them in an archive. Set to "false" if ranlib or ar can generate random libraries.

"osname"
From Oldconfig.U:

This variable contains the operating system name (e.g. sunos, solaris, hpux, etc.). It can be useful later on for setting defaults. Any spaces are replaced with underscores. It is set to a null string if we can't figure it out.

"osvers"
From Oldconfig.U:

This variable contains the operating system version (e.g. 4.1.3, 5.2, etc.). It is primarily used for helping select an appropriate hints file, but might be useful elsewhere for setting defaults. It is set to '' if we can't figure it out. We try to be flexible about how much of the version number to keep, e.g. if 4.1.1, 4.1.2, and 4.1.3 are essentially the same for this package, hints files might just be os_4.0 or os_4.1, etc., not keeping separate files for each little release.

"otherlibdirs"
From otherlibdirs.U:

This variable contains a colon-separated set of paths for the perl binary to search for additional library files or modules. These directories will be tacked to the end of @"INC". Perl will automatically search below each path for version- and architecture-specific directories. See inc_version_list for more details. A value of " " means "none" and is used to preserve this value for the next run through Configure.

"package"
From package.U:

This variable contains the name of the package being constructed. It is primarily intended for the use of later Configure units.

"pager"
From pager.U:

This variable contains the name of the preferred pager on the system. Usual values are (the full pathnames of) more, less, pg, or cat.

"passcat"
From nis.U:

This variable contains a command that produces the text of the /etc/passwd file. This is normally "cat /etc/passwd", but can be "ypcat passwd" when "NIS" is used. On some systems, such as os390, there may be no equivalent command, in which case this variable is unset.

"patchlevel"
From patchlevel.U:

The patchlevel level of this package. The value of patchlevel comes from the patchlevel.h file. In a version number such as 5.6.1, this is the 6. In patchlevel.h, this is referred to as "PERL_VERSION".

"path_sep"
From Unix.U:

This is an old synonym for p_ in Head.U, the character used to separate elements in the command shell search "PATH".

"perl"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the perl program. After Configure runs, the value is reset to a plain "perl" and is not useful.

"perl5"
From perl5.U:

This variable contains the full path (if any) to a previously installed perl5.005 or later suitable for running the script to determine inc_version_list.

"PERL_API_REVISION"
From patchlevel.h:

This number describes the earliest compatible "PERL_REVISION" of Perl ("compatibility" here being defined as sufficient binary/"API" compatibility to run "XS" code built with the older version). Normally this does not change across maintenance releases. Please read the comment in patchlevel.h.

"PERL_API_SUBVERSION"
From patchlevel.h:

This number describes the earliest compatible "PERL_SUBVERSION" of Perl ("compatibility" here being defined as sufficient binary/"API" compatibility to run "XS" code built with the older version). Normally this does not change across maintenance releases. Please read the comment in patchlevel.h.

"PERL_API_VERSION"
From patchlevel.h:

This number describes the earliest compatible "PERL_VERSION" of Perl ("compatibility" here being defined as sufficient binary/"API" compatibility to run "XS" code built with the older version). Normally this does not change across maintenance releases. Please read the comment in patchlevel.h.

"PERL_CONFIG_SH"
From Oldsyms.U:

This is set to "true" in config.sh so that a shell script sourcing config.sh can tell if it has been sourced already.

"PERL_PATCHLEVEL"
From Oldsyms.U:

This symbol reflects the patchlevel, if available. Will usually come from the .patch file, which is available when the perl source tree was fetched with rsync.

"perl_patchlevel"
From patchlevel.U:

This is the Perl patch level, a numeric change identifier, as defined by whichever source code maintenance system is used to maintain the patches; currently Perforce. It does not correlate with the Perl version numbers or the maintenance versus development dichotomy except by also being increasing.

"PERL_REVISION"
From Oldsyms.U:

In a Perl version number such as 5.6.2, this is the 5. This value is manually set in patchlevel.h

"perl_static_inline"
From d_static_inline.U:

This variable defines the "PERL_STATIC_INLINE" symbol to the best-guess incantation to use for static inline functions. Possibilities include static inline (c99) static __inline__ (gcc -ansi) static __inline ("MSVC") static _inline (older "MSVC") static (c89 compilers)

"PERL_SUBVERSION"
From Oldsyms.U:

In a Perl version number such as 5.6.2, this is the 2. Values greater than 50 represent potentially unstable development subversions. This value is manually set in patchlevel.h

"PERL_VERSION"
From Oldsyms.U:

In a Perl version number such as 5.6.2, this is the 6. This value is manually set in patchlevel.h

"perladmin"
From perladmin.U:

Electronic mail address of the perl5 administrator.

"perllibs"
From End.U:

The list of libraries needed by Perl only (any libraries needed by extensions only will by dropped, if using dynamic loading).

"perlpath"
From perlpath.U:

This variable contains the eventual value of the "PERLPATH" symbol, which contains the name of the perl interpreter to be used in shell scripts and in the "eval "exec"" idiom. This variable is not necessarily the pathname of the file containing the perl interpreter; you must append the executable extension (_exe) if it is not already present. Note that Perl code that runs during the Perl build process cannot reference this variable, as Perl may not have been installed, or even if installed, may be a different version of Perl.

"pg"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the pg program. After Configure runs, the value is reset to a plain "pg" and is not useful.

"phostname"
From myhostname.U:

This variable contains the eventual value of the "PHOSTNAME" symbol, which is a command that can be fed to popen() to get the host name. The program should probably not presume that the domain is or isn't there already.

"pidtype"
From pidtype.U:

This variable defines "PIDTYPE" to be something like pid_t, int, ushort, or whatever type is used to declare process ids in the kernel.

"plibpth"
From libpth.U:

Holds the private path used by Configure to find out the libraries. Its value is prepend to libpth. This variable takes care of special machines, like the mips. Usually, it should be empty.

"pmake"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"pr"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"prefix"
From prefix.U:

This variable holds the name of the directory below which the user will install the package. Usually, this is /usr/local, and executables go in /usr/local/bin, library stuff in /usr/local/lib, man pages in /usr/local/man, etc. It is only used to set defaults for things in bin.U, mansrc.U, privlib.U, or scriptdir.U.

"prefixexp"
From prefix.U:

This variable holds the full absolute path of the directory below which the user will install the package. Derived from prefix.

"privlib"
From privlib.U:

This variable contains the eventual value of the "PRIVLIB" symbol, which is the name of the private library for this package. It may have a ~ on the front. It is up to the makefile to eventually create this directory while performing installation (with ~ substitution).

"privlibexp"
From privlib.U:

This variable is the ~name expanded version of privlib, so that you may use it directly in Makefiles or shell scripts.

"procselfexe"
From d_procselfexe.U:

If d_procselfexe is defined, $procselfexe is the filename of the symbolic link pointing to the absolute pathname of the executing program.

"ptrsize"
From ptrsize.U:

This variable contains the value of the "PTRSIZE" symbol, which indicates to the C program how many bytes there are in a pointer.

"quadkind"
From quadtype.U:

This variable, if defined, encodes the type of a quad: 1 = int, 2 = long, 3 = long long, 4 = int64_t.

"quadtype"
From quadtype.U:

This variable defines Quad_t to be something like long, int, long long, int64_t, or whatever type is used for 64-bit integers.

"randbits"
From randfunc.U:

Indicates how many bits are produced by the function used to generate normalized random numbers.

"randfunc"
From randfunc.U:

Indicates the name of the random number function to use. Values include drand48, random, and rand. In C programs, the "Drand01" macro is defined to generate uniformly distributed random numbers over the range [0., 1.[ (see drand01 and nrand).

"random_r_proto"
From d_random_r.U:

This variable encodes the prototype of random_r. It is zero if d_random_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_random_r is defined.

"randseedtype"
From randfunc.U:

Indicates the type of the argument of the seedfunc.

"ranlib"
From orderlib.U:

This variable is set to the pathname of the ranlib program, if it is needed to generate random libraries. Set to ":" if ar can generate random libraries or if random libraries are not supported

"rd_nodata"
From nblock_io.U:

This variable holds the return code from read() when no data is present. It should be -1, but some systems return 0 when "O_NDELAY" is used, which is a shame because you cannot make the difference between no data and an EOF.. Sigh!

"readdir64_r_proto"
From d_readdir64_r.U:

This variable encodes the prototype of readdir64_r. It is zero if d_readdir64_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_readdir64_r is defined.

"readdir_r_proto"
From d_readdir_r.U:

This variable encodes the prototype of readdir_r. It is zero if d_readdir_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_readdir_r is defined.

"revision"
From patchlevel.U:

The value of revision comes from the patchlevel.h file. In a version number such as 5.6.1, this is the 5. In patchlevel.h, this is referred to as "PERL_REVISION".

"rm"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the rm program. After Configure runs, the value is reset to a plain "rm" and is not useful.

"rm_try"
From Unix.U:

This is a cleanup variable for try test programs. Internal Configure use only.

"rmail"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"run"
From Cross.U:

This variable contains the command used by Configure to copy and execute a cross-compiled executable in the target host. Useful and available only during Perl build. Empty string '' if not cross-compiling.

"runnm"
From usenm.U:

This variable contains "true" or "false" depending whether the nm extraction should be performed or not, according to the value of usenm and the flags on the Configure command line.

"sched_yield"
From d_pthread_y.U:

This variable defines the way to yield the execution of the current thread.

"scriptdir"
From scriptdir.U:

This variable holds the name of the directory in which the user wants to put publicly scripts for the package in question. It is either the same directory as for binaries, or a special one that can be mounted across different architectures, like /usr/share. Programs must be prepared to deal with ~name expansion.

"scriptdirexp"
From scriptdir.U:

This variable is the same as scriptdir, but is filename expanded at configuration time, for programs not wanting to bother with it.

"sed"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the sed program. After Configure runs, the value is reset to a plain "sed" and is not useful.

"seedfunc"
From randfunc.U:

Indicates the random number generating seed function. Values include srand48, srandom, and srand.

"selectminbits"
From selectminbits.U:

This variable holds the minimum number of bits operated by select. That is, if you do select(n, ...), how many bits at least will be cleared in the masks if some activity is detected. Usually this is either n or 32*ceil(n/32), especially many little-endians do the latter. This is only useful if you have select(), naturally.

"selecttype"
From selecttype.U:

This variable holds the type used for the 2nd, 3rd, and 4th arguments to select. Usually, this is "fd_set *", if "HAS_FD_SET" is defined, and "int *" otherwise. This is only useful if you have select(), naturally.

"sendmail"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"setgrent_r_proto"
From d_setgrent_r.U:

This variable encodes the prototype of setgrent_r. It is zero if d_setgrent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_setgrent_r is defined.

"sethostent_r_proto"
From d_sethostent_r.U:

This variable encodes the prototype of sethostent_r. It is zero if d_sethostent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_sethostent_r is defined.

"setlocale_r_proto"
From d_setlocale_r.U:

This variable encodes the prototype of setlocale_r. It is zero if d_setlocale_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_setlocale_r is defined.

"setnetent_r_proto"
From d_setnetent_r.U:

This variable encodes the prototype of setnetent_r. It is zero if d_setnetent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_setnetent_r is defined.

"setprotoent_r_proto"
From d_setprotoent_r.U:

This variable encodes the prototype of setprotoent_r. It is zero if d_setprotoent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_setprotoent_r is defined.

"setpwent_r_proto"
From d_setpwent_r.U:

This variable encodes the prototype of setpwent_r. It is zero if d_setpwent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_setpwent_r is defined.

"setservent_r_proto"
From d_setservent_r.U:

This variable encodes the prototype of setservent_r. It is zero if d_setservent_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_setservent_r is defined.

"sGMTIME_max"
From time_size.U:

This variable defines the maximum value of the time_t offset that the system function gmtime () accepts

"sGMTIME_min"
From time_size.U:

This variable defines the minimum value of the time_t offset that the system function gmtime () accepts

"sh"
From sh.U:

This variable contains the full pathname of the shell used on this system to execute Bourne shell scripts. Usually, this will be /bin/sh, though it's possible that some systems will have /bin/ksh, /bin/pdksh, /bin/ash, /bin/bash, or even something such as D:/bin/sh.exe. This unit comes before Options.U, so you can't set sh with a "-D" option, though you can override this (and startsh) with "-O -Dsh=/bin/whatever -Dstartsh=whatever"

"shar"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"sharpbang"
From spitshell.U:

This variable contains the string #! if this system supports that construct.

"shmattype"
From d_shmat.U:

This symbol contains the type of pointer returned by shmat(). It can be "void *" or "char *".

"shortsize"
From intsize.U:

This variable contains the value of the "SHORTSIZE" symbol which indicates to the C program how many bytes there are in a short.

"shrpenv"
From libperl.U:

If the user builds a shared libperl.so, then we need to tell the "perl" executable where it will be able to find the installed libperl.so. One way to do this on some systems is to set the environment variable "LD_RUN_PATH" to the directory that will be the final location of the shared libperl.so. The makefile can use this with something like $shrpenv $("CC") -o perl perlmain.o $libperl $libs Typical values are shrpenv="env "LD_RUN_PATH"=$archlibexp/"CORE"" or shrpenv='' See the main perl Makefile.SH for actual working usage.

Alternatively, we might be able to use a command line option such as -R $archlibexp/"CORE" (Solaris) or -Wl,-rpath $archlibexp/"CORE" (Linux).

"shsharp"
From spitshell.U:

This variable tells further Configure units whether your sh can handle # comments.

"sig_count"
From sig_name.U:

This variable holds a number larger than the largest valid signal number. This is usually the same as the "NSIG" macro.

"sig_name"
From sig_name.U:

This variable holds the signal names, space separated. The leading "SIG" in signal name is removed. A "ZERO" is prepended to the list. This is currently not used, sig_name_init is used instead.

"sig_name_init"
From sig_name.U:

This variable holds the signal names, enclosed in double quotes and separated by commas, suitable for use in the "SIG_NAME" definition below. A "ZERO" is prepended to the list, and the list is terminated with a plain 0. The leading "SIG" in signal names is removed. See sig_num.

"sig_num"
From sig_name.U:

This variable holds the signal numbers, space separated. A "ZERO" is prepended to the list (corresponding to the fake "SIGZERO"). Those numbers correspond to the value of the signal listed in the same place within the sig_name list. This is currently not used, sig_num_init is used instead.

"sig_num_init"
From sig_name.U:

This variable holds the signal numbers, enclosed in double quotes and separated by commas, suitable for use in the "SIG_NUM" definition below. A "ZERO" is prepended to the list, and the list is terminated with a plain 0.

"sig_size"
From sig_name.U:

This variable contains the number of elements of the sig_name and sig_num arrays.

"signal_t"
From d_voidsig.U:

This variable holds the type of the signal handler (void or int).

"sitearch"
From sitearch.U:

This variable contains the eventual value of the "SITEARCH" symbol, which is the name of the private library for this package. It may have a ~ on the front. It is up to the makefile to eventually create this directory while performing installation (with ~ substitution). The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local architecture-dependent modules in this directory with MakeMaker Makefile.PL or equivalent. See "INSTALL" for details.

"sitearchexp"
From sitearch.U:

This variable is the ~name expanded version of sitearch, so that you may use it directly in Makefiles or shell scripts.

"sitebin"
From sitebin.U:

This variable holds the name of the directory in which the user wants to put add-on publicly executable files for the package in question. It is most often a local directory such as /usr/local/bin. Programs using this variable must be prepared to deal with ~name substitution. The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local executables in this directory with MakeMaker Makefile.PL or equivalent. See "INSTALL" for details.

"sitebinexp"
From sitebin.U:

This is the same as the sitebin variable, but is filename expanded at configuration time, for use in your makefiles.

"sitehtml1dir"
From sitehtml1dir.U:

This variable contains the name of the directory in which site-specific html source pages are to be put. It is the responsibility of the Makefile.SH to get the value of this into the proper command. You must be prepared to do the ~name expansion yourself. The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local html pages in this directory with MakeMaker Makefile.PL or equivalent. See "INSTALL" for details.

"sitehtml1direxp"
From sitehtml1dir.U:

This variable is the same as the sitehtml1dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

"sitehtml3dir"
From sitehtml3dir.U:

This variable contains the name of the directory in which site-specific library html source pages are to be put. It is the responsibility of the Makefile.SH to get the value of this into the proper command. You must be prepared to do the ~name expansion yourself. The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local library html pages in this directory with MakeMaker Makefile.PL or equivalent. See "INSTALL" for details.

"sitehtml3direxp"
From sitehtml3dir.U:

This variable is the same as the sitehtml3dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

"sitelib"
From sitelib.U:

This variable contains the eventual value of the "SITELIB" symbol, which is the name of the private library for this package. It may have a ~ on the front. It is up to the makefile to eventually create this directory while performing installation (with ~ substitution). The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local architecture-independent modules in this directory with MakeMaker Makefile.PL or equivalent. See "INSTALL" for details.

"sitelib_stem"
From sitelib.U:

This variable is $sitelibexp with any trailing version-specific component removed. The elements in inc_version_list (inc_version_list.U) can be tacked onto this variable to generate a list of directories to search.

"sitelibexp"
From sitelib.U:

This variable is the ~name expanded version of sitelib, so that you may use it directly in Makefiles or shell scripts.

"siteman1dir"
From siteman1dir.U:

This variable contains the name of the directory in which site-specific manual source pages are to be put. It is the responsibility of the Makefile.SH to get the value of this into the proper command. You must be prepared to do the ~name expansion yourself. The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local man1 pages in this directory with MakeMaker Makefile.PL or equivalent. See "INSTALL" for details.

"siteman1direxp"
From siteman1dir.U:

This variable is the same as the siteman1dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

"siteman3dir"
From siteman3dir.U:

This variable contains the name of the directory in which site-specific library man source pages are to be put. It is the responsibility of the Makefile.SH to get the value of this into the proper command. You must be prepared to do the ~name expansion yourself. The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local man3 pages in this directory with MakeMaker Makefile.PL or equivalent. See "INSTALL" for details.

"siteman3direxp"
From siteman3dir.U:

This variable is the same as the siteman3dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

"siteprefix"
From siteprefix.U:

This variable holds the full absolute path of the directory below which the user will install add-on packages. See "INSTALL" for usage and examples.

"siteprefixexp"
From siteprefix.U:

This variable holds the full absolute path of the directory below which the user will install add-on packages. Derived from siteprefix.

"sitescript"
From sitescript.U:

This variable holds the name of the directory in which the user wants to put add-on publicly executable files for the package in question. It is most often a local directory such as /usr/local/bin. Programs using this variable must be prepared to deal with ~name substitution. The standard distribution will put nothing in this directory. After perl has been installed, users may install their own local scripts in this directory with MakeMaker Makefile.PL or equivalent. See "INSTALL" for details.

"sitescriptexp"
From sitescript.U:

This is the same as the sitescript variable, but is filename expanded at configuration time, for use in your makefiles.

"sizesize"
From sizesize.U:

This variable contains the size of a sizetype in bytes.

"sizetype"
From sizetype.U:

This variable defines sizetype to be something like size_t, unsigned long, or whatever type is used to declare length parameters for string functions.

"sleep"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"sLOCALTIME_max"
From time_size.U:

This variable defines the maximum value of the time_t offset that the system function localtime () accepts

"sLOCALTIME_min"
From time_size.U:

This variable defines the minimum value of the time_t offset that the system function localtime () accepts

"smail"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"so"
From so.U:

This variable holds the extension used to identify shared libraries (also known as shared objects) on the system. Usually set to "so".

"sockethdr"
From d_socket.U:

This variable has any cpp "-I" flags needed for socket support.

"socketlib"
From d_socket.U:

This variable has the names of any libraries needed for socket support.

"socksizetype"
From socksizetype.U:

This variable holds the type used for the size argument for various socket calls like accept. Usual values include socklen_t, size_t, and int.

"sort"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the sort program. After Configure runs, the value is reset to a plain "sort" and is not useful.

"spackage"
From package.U:

This variable contains the name of the package being constructed, with the first letter uppercased, i.e. suitable for starting sentences.

"spitshell"
From spitshell.U:

This variable contains the command necessary to spit out a runnable shell on this system. It is either cat or a grep "-v" for # comments.

"sPRId64"
From quadfio.U:

This variable, if defined, contains the string used by stdio to format 64-bit decimal numbers (format "d") for output.

"sPRIeldbl"
From longdblfio.U:

This variable, if defined, contains the string used by stdio to format long doubles (format "e") for output.

"sPRIEUldbl"
From longdblfio.U:

This variable, if defined, contains the string used by stdio to format long doubles (format "E") for output. The "U" in the name is to separate this from sPRIeldbl so that even case-blind systems can see the difference.

"sPRIfldbl"
From longdblfio.U:

This variable, if defined, contains the string used by stdio to format long doubles (format "f") for output.

"sPRIFUldbl"
From longdblfio.U:

This variable, if defined, contains the string used by stdio to format long doubles (format "F") for output. The "U" in the name is to separate this from sPRIfldbl so that even case-blind systems can see the difference.

"sPRIgldbl"
From longdblfio.U:

This variable, if defined, contains the string used by stdio to format long doubles (format "g") for output.

"sPRIGUldbl"
From longdblfio.U:

This variable, if defined, contains the string used by stdio to format long doubles (format "G") for output. The "U" in the name is to separate this from sPRIgldbl so that even case-blind systems can see the difference.

"sPRIi64"
From quadfio.U:

This variable, if defined, contains the string used by stdio to format 64-bit decimal numbers (format "i") for output.

"sPRIo64"
From quadfio.U:

This variable, if defined, contains the string used by stdio to format 64-bit octal numbers (format "o") for output.

"sPRIu64"
From quadfio.U:

This variable, if defined, contains the string used by stdio to format 64-bit unsigned decimal numbers (format "u") for output.

"sPRIx64"
From quadfio.U:

This variable, if defined, contains the string used by stdio to format 64-bit hexadecimal numbers (format "x") for output.

"sPRIXU64"
From quadfio.U:

This variable, if defined, contains the string used by stdio to format 64-bit hExADECimAl numbers (format "X") for output. The "U" in the name is to separate this from sPRIx64 so that even case-blind systems can see the difference.

"srand48_r_proto"
From d_srand48_r.U:

This variable encodes the prototype of srand48_r. It is zero if d_srand48_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_srand48_r is defined.

"srandom_r_proto"
From d_srandom_r.U:

This variable encodes the prototype of srandom_r. It is zero if d_srandom_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_srandom_r is defined.

"src"
From src.U:

This variable holds the (possibly relative) path of the package source. It is up to the Makefile to use this variable and set "VPATH" accordingly to find the sources remotely. Use $pkgsrc to have an absolute path.

"sSCNfldbl"
From longdblfio.U:

This variable, if defined, contains the string used by stdio to format long doubles (format "f") for input.

"ssizetype"
From ssizetype.U:

This variable defines ssizetype to be something like ssize_t, long or int. It is used by functions that return a count of bytes or an error condition. It must be a signed type. We will pick a type such that sizeof(SSize_t) == sizeof(Size_t).

"st_ino_sign"
From st_ino_def.U:

This variable contains the signedness of struct stat's st_ino. 1 for unsigned, -1 for signed.

"st_ino_size"
From st_ino_def.U:

This variable contains the size of struct stat's st_ino in bytes.

"startperl"
From startperl.U:

This variable contains the string to put on the front of a perl script to make sure (hopefully) that it runs with perl and not some shell. Of course, that leading line must be followed by the classical perl idiom: eval 'exec perl -S $0 ${1+$@}' if $running_under_some_shell; to guarantee perl startup should the shell execute the script. Note that this magic incantation is not understood by csh.

"startsh"
From startsh.U:

This variable contains the string to put on the front of a shell script to make sure (hopefully) that it runs with sh and not some other shell.

"static_ext"
From Extensions.U:

This variable holds a list of "XS" extension files we want to link statically into the package. It is used by Makefile.

"stdchar"
From stdchar.U:

This variable conditionally defines "STDCHAR" to be the type of char used in stdio.h. It has the values "unsigned char" or "char".

"stdio_base"
From d_stdstdio.U:

This variable defines how, given a "FILE" pointer, fp, to access the _base field (or equivalent) of stdio.h's "FILE" structure. This will be used to define the macro FILE_base(fp).

"stdio_bufsiz"
From d_stdstdio.U:

This variable defines how, given a "FILE" pointer, fp, to determine the number of bytes store in the I/O buffer pointer to by the _base field (or equivalent) of stdio.h's "FILE" structure. This will be used to define the macro FILE_bufsiz(fp).

"stdio_cnt"
From d_stdstdio.U:

This variable defines how, given a "FILE" pointer, fp, to access the _cnt field (or equivalent) of stdio.h's "FILE" structure. This will be used to define the macro FILE_cnt(fp).

"stdio_filbuf"
From d_stdstdio.U:

This variable defines how, given a "FILE" pointer, fp, to tell stdio to refill its internal buffers (?). This will be used to define the macro FILE_filbuf(fp).

"stdio_ptr"
From d_stdstdio.U:

This variable defines how, given a "FILE" pointer, fp, to access the _ptr field (or equivalent) of stdio.h's "FILE" structure. This will be used to define the macro FILE_ptr(fp).

"stdio_stream_array"
From stdio_streams.U:

This variable tells the name of the array holding the stdio streams. Usual values include _iob, __iob, and __sF.

"strerror_r_proto"
From d_strerror_r.U:

This variable encodes the prototype of strerror_r. It is zero if d_strerror_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_strerror_r is defined.

"submit"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"subversion"
From patchlevel.U:

The subversion level of this package. The value of subversion comes from the patchlevel.h file. In a version number such as 5.6.1, this is the 1. In patchlevel.h, this is referred to as "PERL_SUBVERSION". This is unique to perl.

"sysman"
From sysman.U:

This variable holds the place where the manual is located on this system. It is not the place where the user wants to put his manual pages. Rather it is the place where Configure may look to find manual for unix commands (section 1 of the manual usually). See mansrc.

"sysroot"
From Sysroot.U:

This variable is empty unless supplied by the Configure user. It can contain a path to an alternative root directory, under which headers and libraries for the compilation target can be found. This is generally used when cross-compiling using a gcc-like compiler.

"tail"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"tar"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"targetarch"
From Cross.U:

If cross-compiling, this variable contains the target architecture. If not, this will be empty.

"targetdir"
From Cross.U:

This variable contains a path that will be created on the target host using targetmkdir, and then used to copy the cross-compiled executables to. Defaults to /tmp if not set.

"targetenv"
From Cross.U:

If cross-compiling, this variable can be used to modify the environment on the target system. However, how and where it's used, and even if it's used at all, is entirely dependent on both the transport mechanism (targetrun) and what the target system is. Unless the relevant documentation says otherwise, it is genereally not useful.

"targethost"
From Cross.U:

This variable contains the name of a separate host machine that can be used to run compiled test programs and perl tests on. Set to empty string if not in use.

"targetmkdir"
From Cross.U:

This variable contains the command used by Configure to create a new directory on the target host.

"targetport"
From Cross.U:

This variable contains the number of a network port to be used to connect to the host in targethost, if unset defaults to 22 for ssh.

"targetsh"
From sh.U:

If cross-compiling, this variable contains the location of sh on the target system. If not, this will be the same as $sh.

"tbl"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"tee"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"test"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the test program. After Configure runs, the value is reset to a plain "test" and is not useful.

"timeincl"
From i_time.U:

This variable holds the full path of the included time header(s).

"timetype"
From d_time.U:

This variable holds the type returned by time(). It can be long, or time_t on "BSD" sites (in which case <sys/types.h> should be included). Anyway, the type Time_t should be used.

"tmpnam_r_proto"
From d_tmpnam_r.U:

This variable encodes the prototype of tmpnam_r. It is zero if d_tmpnam_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_tmpnam_r is defined.

"to"
From Cross.U:

This variable contains the command used by Configure to copy to from the target host. Useful and available only during Perl build. The string ":" if not cross-compiling.

"touch"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the touch program. After Configure runs, the value is reset to a plain "touch" and is not useful.

"tr"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the tr program. After Configure runs, the value is reset to a plain "tr" and is not useful.

"trnl"
From trnl.U:

This variable contains the value to be passed to the tr(1) command to transliterate a newline. Typical values are "\012" and "\n". This is needed for "EBCDIC" systems where newline is not necessarily "\012".

"troff"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"ttyname_r_proto"
From d_ttyname_r.U:

This variable encodes the prototype of ttyname_r. It is zero if d_ttyname_r is undef, and one of the "REENTRANT_PROTO_T_ABC" macros of reentr.h if d_ttyname_r is defined.

"u16size"
From perlxv.U:

This variable is the size of an U16 in bytes.

"u16type"
From perlxv.U:

This variable contains the C type used for Perl's U16.

"u32size"
From perlxv.U:

This variable is the size of an U32 in bytes.

"u32type"
From perlxv.U:

This variable contains the C type used for Perl's U32.

"u64size"
From perlxv.U:

This variable is the size of an U64 in bytes.

"u64type"
From perlxv.U:

This variable contains the C type used for Perl's U64.

"u8size"
From perlxv.U:

This variable is the size of an U8 in bytes.

"u8type"
From perlxv.U:

This variable contains the C type used for Perl's U8.

"uidformat"
From uidf.U:

This variable contains the format string used for printing a Uid_t.

"uidsign"
From uidsign.U:

This variable contains the signedness of a uidtype. 1 for unsigned, -1 for signed.

"uidsize"
From uidsize.U:

This variable contains the size of a uidtype in bytes.

"uidtype"
From uidtype.U:

This variable defines Uid_t to be something like uid_t, int, ushort, or whatever type is used to declare user ids in the kernel.

"uname"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the uname program. After Configure runs, the value is reset to a plain "uname" and is not useful.

"uniq"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the uniq program. After Configure runs, the value is reset to a plain "uniq" and is not useful.

"uquadtype"
From quadtype.U:

This variable defines Uquad_t to be something like unsigned long, unsigned int, unsigned long long, uint64_t, or whatever type is used for 64-bit integers.

"use64bitall"
From use64bits.U:

This variable conditionally defines the USE_64_BIT_ALL symbol, and indicates that 64-bit integer types should be used when available. The maximal possible 64-bitness is employed: LP64 or ILP64, meaning that you will be able to use more than 2 gigabytes of memory. This mode is even more binary incompatible than USE_64_BIT_INT. You may not be able to run the resulting executable in a 32-bit "CPU" at all or you may need at least to reboot your "OS" to 64-bit mode.

"use64bitint"
From use64bits.U:

This variable conditionally defines the USE_64_BIT_INT symbol, and indicates that 64-bit integer types should be used when available. The minimal possible 64-bitness is employed, just enough to get 64-bit integers into Perl. This may mean using for example "long longs", while your memory may still be limited to 2 gigabytes.

"usecbacktrace"
From usebacktrace.U:

This variable indicates whether we are compiling with backtrace support.

"usecrosscompile"
From Cross.U:

This variable conditionally defines the "USE_CROSS_COMPILE" symbol, and indicates that Perl has been cross-compiled.

"usedefaultstrict"
From usedefaultstrict.U:

This setting provides a mechanism for perl developers to enable strict by default. These defaults do not apply when perl is run via -e or -E.

"usedevel"
From Devel.U:

This variable indicates that Perl was configured with development features enabled. This should not be done for production builds.

"usedl"
From dlsrc.U:

This variable indicates if the system supports dynamic loading of some sort. See also dlsrc and dlobj.

"usedtrace"
From usedtrace.U:

This variable indicates whether we are compiling with dtrace support. See also dtrace.

"usefaststdio"
From usefaststdio.U:

This variable conditionally defines the "USE_FAST_STDIO" symbol, and indicates that Perl should be built to use "fast stdio". Defaults to define in Perls 5.8 and earlier, to undef later.

"useithreads"
From usethreads.U:

This variable conditionally defines the "USE_ITHREADS" symbol, and indicates that Perl should be built to use the interpreter-based threading implementation.

"usekernprocpathname"
From usekernprocpathname.U:

This variable, indicates that we can use sysctl with "KERN_PROC_PATHNAME" to get a full path for the executable, and hence convert $^X to an absolute path.

"uselanginfo"
From Extensions.U:

This variable holds either "true" or "false" to indicate whether the I18N::Langinfo extension should be used. The sole use for this currently is to allow an easy mechanism for users to skip this extension from the Configure command line.

"uselargefiles"
From uselfs.U:

This variable conditionally defines the "USE_LARGE_FILES" symbol, and indicates that large file interfaces should be used when available.

"uselongdouble"
From uselongdbl.U:

This variable conditionally defines the "USE_LONG_DOUBLE" symbol, and indicates that long doubles should be used when available.

"usemallocwrap"
From mallocsrc.U:

This variable contains y if we are wrapping malloc to prevent integer overflow during size calculations.

"usemorebits"
From usemorebits.U:

This variable conditionally defines the "USE_MORE_BITS" symbol, and indicates that explicit 64-bit interfaces and long doubles should be used when available.

"usemultiplicity"
From usemultiplicity.U:

This variable conditionally defines the "MULTIPLICITY" symbol, and indicates that Perl should be built to use multiplicity.

"usemymalloc"
From mallocsrc.U:

This variable contains y if the malloc that comes with this package is desired over the system's version of malloc. People often include special versions of malloc for efficiency, but such versions are often less portable. See also mallocsrc and mallocobj. If this is "y", then -lmalloc is removed from $libs.

"usenm"
From usenm.U:

This variable contains "true" or "false" depending whether the nm extraction is wanted or not.

"usensgetexecutablepath"
From usensgetexecutablepath.U:

This symbol, if defined, indicates that we can use _NSGetExecutablePath and realpath to get a full path for the executable, and hence convert $^X to an absolute path.

"useopcode"
From Extensions.U:

This variable holds either "true" or "false" to indicate whether the Opcode extension should be used. The sole use for this currently is to allow an easy mechanism for users to skip the Opcode extension from the Configure command line.

"useperlio"
From useperlio.U:

This variable conditionally defines the "USE_PERLIO" symbol, and indicates that the PerlIO abstraction should be used throughout.

"useposix"
From Extensions.U:

This variable holds either "true" or "false" to indicate whether the "POSIX" extension should be used. The sole use for this currently is to allow an easy mechanism for hints files to indicate that "POSIX" will not compile on a particular system.

"usequadmath"
From usequadmath.U:

This variable conditionally defines the "USE_QUADMATH" symbol, and indicates that the quadmath library __float128 long doubles should be used when available.

"usereentrant"
From usethreads.U:

This variable conditionally defines the "USE_REENTRANT_API" symbol, which indicates that the thread code may try to use the various _r versions of library functions. This is only potentially meaningful if usethreads is set and is very experimental, it is not even prompted for.

"userelocatableinc"
From bin.U:

This variable is set to true to indicate that perl should relocate @"INC" entries at runtime based on the path to the perl binary. Any @"INC" paths starting .../ are relocated relative to the directory containing the perl binary, and a logical cleanup of the path is then made around the join point (removing dir/../ pairs)

"useshrplib"
From libperl.U:

This variable is set to "true" if the user wishes to build a shared libperl, and "false" otherwise.

"usesitecustomize"
From d_sitecustomize.U:

This variable is set to true when the user requires a mechanism that allows the sysadmin to add entries to @"INC" at runtime. This variable being set, makes perl run $sitelib/sitecustomize.pl at startup.

"usesocks"
From usesocks.U:

This variable conditionally defines the "USE_SOCKS" symbol, and indicates that Perl should be built to use "SOCKS".

"usethreads"
From usethreads.U:

This variable conditionally defines the "USE_THREADS" symbol, and indicates that Perl should be built to use threads.

"usevendorprefix"
From vendorprefix.U:

This variable tells whether the vendorprefix and consequently other vendor* paths are in use.

"useversionedarchname"
From archname.U:

This variable indicates whether to include the $api_versionstring as a component of the $archname.

"usevfork"
From d_vfork.U:

This variable is set to true when the user accepts to use vfork. It is set to false when no vfork is available or when the user explicitly requests not to use vfork.

"usrinc"
From usrinc.U:

This variable holds the path of the include files, which is usually /usr/include. It is mainly used by other Configure units.

"uuname"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"uvoformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "UV" as an unsigned octal integer.

"uvsize"
From perlxv.U:

This variable is the size of a "UV" in bytes.

"uvtype"
From perlxv.U:

This variable contains the C type used for Perl's "UV".

"uvuformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "UV" as an unsigned decimal integer.

"uvxformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "UV" as an unsigned hexadecimal integer in lowercase abcdef.

"uvXUformat"
From perlxvf.U:

This variable contains the format string used for printing a Perl "UV" as an unsigned hexadecimal integer in uppercase "ABCDEF".

"vendorarch"
From vendorarch.U:

This variable contains the value of the "PERL_VENDORARCH" symbol. It may have a ~ on the front. The standard distribution will put nothing in this directory. Vendors who distribute perl may wish to place their own architecture-dependent modules and extensions in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent. See "INSTALL" for details.

"vendorarchexp"
From vendorarch.U:

This variable is the ~name expanded version of vendorarch, so that you may use it directly in Makefiles or shell scripts.

"vendorbin"
From vendorbin.U:

This variable contains the eventual value of the "VENDORBIN" symbol. It may have a ~ on the front. The standard distribution will put nothing in this directory. Vendors who distribute perl may wish to place additional binaries in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent. See "INSTALL" for details.

"vendorbinexp"
From vendorbin.U:

This variable is the ~name expanded version of vendorbin, so that you may use it directly in Makefiles or shell scripts.

"vendorhtml1dir"
From vendorhtml1dir.U:

This variable contains the name of the directory for html pages. It may have a ~ on the front. The standard distribution will put nothing in this directory. Vendors who distribute perl may wish to place their own html pages in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent. See "INSTALL" for details.

"vendorhtml1direxp"
From vendorhtml1dir.U:

This variable is the ~name expanded version of vendorhtml1dir, so that you may use it directly in Makefiles or shell scripts.

"vendorhtml3dir"
From vendorhtml3dir.U:

This variable contains the name of the directory for html library pages. It may have a ~ on the front. The standard distribution will put nothing in this directory. Vendors who distribute perl may wish to place their own html pages for modules and extensions in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent. See "INSTALL" for details.

"vendorhtml3direxp"
From vendorhtml3dir.U:

This variable is the ~name expanded version of vendorhtml3dir, so that you may use it directly in Makefiles or shell scripts.

"vendorlib"
From vendorlib.U:

This variable contains the eventual value of the "VENDORLIB" symbol, which is the name of the private library for this package. The standard distribution will put nothing in this directory. Vendors who distribute perl may wish to place their own modules in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent. See "INSTALL" for details.

"vendorlib_stem"
From vendorlib.U:

This variable is $vendorlibexp with any trailing version-specific component removed. The elements in inc_version_list (inc_version_list.U) can be tacked onto this variable to generate a list of directories to search.

"vendorlibexp"
From vendorlib.U:

This variable is the ~name expanded version of vendorlib, so that you may use it directly in Makefiles or shell scripts.

"vendorman1dir"
From vendorman1dir.U:

This variable contains the name of the directory for man1 pages. It may have a ~ on the front. The standard distribution will put nothing in this directory. Vendors who distribute perl may wish to place their own man1 pages in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent. See "INSTALL" for details.

"vendorman1direxp"
From vendorman1dir.U:

This variable is the ~name expanded version of vendorman1dir, so that you may use it directly in Makefiles or shell scripts.

"vendorman3dir"
From vendorman3dir.U:

This variable contains the name of the directory for man3 pages. It may have a ~ on the front. The standard distribution will put nothing in this directory. Vendors who distribute perl may wish to place their own man3 pages in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent. See "INSTALL" for details.

"vendorman3direxp"
From vendorman3dir.U:

This variable is the ~name expanded version of vendorman3dir, so that you may use it directly in Makefiles or shell scripts.

"vendorprefix"
From vendorprefix.U:

This variable holds the full absolute path of the directory below which the vendor will install add-on packages. See "INSTALL" for usage and examples.

"vendorprefixexp"
From vendorprefix.U:

This variable holds the full absolute path of the directory below which the vendor will install add-on packages. Derived from vendorprefix.

"vendorscript"
From vendorscript.U:

This variable contains the eventual value of the "VENDORSCRIPT" symbol. It may have a ~ on the front. The standard distribution will put nothing in this directory. Vendors who distribute perl may wish to place additional executable scripts in this directory with MakeMaker Makefile.PL "INSTALLDIRS"=vendor or equivalent. See "INSTALL" for details.

"vendorscriptexp"
From vendorscript.U:

This variable is the ~name expanded version of vendorscript, so that you may use it directly in Makefiles or shell scripts.

"version"
From patchlevel.U:

The full version number of this package, such as 5.6.1 (or 5_6_1). This combines revision, patchlevel, and subversion to get the full version number, including any possible subversions. This is suitable for use as a directory name, and hence is filesystem dependent.

"version_patchlevel_string"
From patchlevel.U:

This is a string combining version, subversion and perl_patchlevel (if perl_patchlevel is non-zero). It is typically something like 'version 7 subversion 1' or 'version 7 subversion 1 patchlevel 11224' It is computed here to avoid duplication of code in myconfig.SH and lib/Config.pm.

"versiononly"
From versiononly.U:

If set, this symbol indicates that only the version-specific components of a perl installation should be installed. This may be useful for making a test installation of a new version without disturbing the existing installation. Setting versiononly is equivalent to setting installperl's -v option. In particular, the non-versioned scripts and programs such as a2p, c2ph, h2xs, pod2*, and perldoc are not installed (see "INSTALL" for a more complete list). Nor are the man pages installed. Usually, this is undef.

"vi"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"xlibpth"
From libpth.U:

This variable holds extra path (space-separated) used to find libraries on this platform, for example "CPU"-specific libraries (on multi-"CPU" platforms) may be listed here.

"yacc"
From yacc.U:

This variable holds the name of the compiler compiler we want to use in the Makefile. It can be yacc, byacc, or bison -y.

"yaccflags"
From yacc.U:

This variable contains any additional yacc flags desired by the user. It is up to the Makefile to use this.

"zcat"
From Loc.U:

This variable is defined but not used by Configure. The value is the empty string and is not useful.

"zip"
From Loc.U:

This variable is used internally by Configure to determine the full pathname (if any) of the zip program. After Configure runs, the value is reset to a plain "zip" and is not useful.

Information on the git commit from which the current perl binary was compiled can be found in the variable $Config::Git_Data. The variable is a structured string that looks something like this:

  git_commit_id='ea0c2dbd5f5ac6845ecc7ec6696415bf8e27bd52'
  git_describe='GitLive-blead-1076-gea0c2db'
  git_branch='smartmatch'
  git_uncommitted_changes=''
  git_commit_id_title='Commit id:'
  git_commit_date='2009-05-09 17:47:31 +0200'

Its format is not guaranteed not to change over time.

This module contains a good example of how to use tie to implement a cache and an example of how to make a tied variable readonly to those outside of it.

2021-10-20 perl v5.30.3