GLOB(3) Library Functions Manual GLOB(3)

glob, glob_b, globfree — generate pathnames matching a pattern

#include <glob.h>

int
glob(const char * restrict pattern, int flags, int (*errfunc)(const char *epath, int errno), glob_t * restrict pglob);

int
glob_b(const char * restrict pattern, int flags, int (^errblk)(const char *epath, int errno), glob_t * restrict pglob);

void
globfree(glob_t *pglob);

The () function is a pathname generator that implements the rules for file name pattern matching used by the shell.

The include file <glob.h> defines the structure type glob_t, which contains at least the following fields:

typedef struct {
	size_t gl_pathc;	/* count of total paths so far */
	int gl_matchc;		/* count of paths matching pattern */
	size_t gl_offs;		/* reserved at beginning of gl_pathv */
	int gl_flags;		/* returned flags */
	char **gl_pathv;	/* list of paths matching pattern */
} glob_t;

The argument pattern is a pointer to a pathname pattern to be expanded. The () argument matches all accessible pathnames against the pattern and creates a list of the pathnames that match. In order to have access to a pathname, glob() requires search permission on every component of a path except the last and read permission on each directory of any filename component of pattern that contains any of the special characters ‘*’, ‘?’ or ‘[’.

The () argument stores the number of matched pathnames into the gl_pathc field, and a pointer to a list of pointers to pathnames into the gl_pathv field. The first pointer after the last pathname is NULL. If the pattern does not match any pathnames, the returned number of matched paths is set to zero.

It is the caller's responsibility to create the structure pointed to by pglob. The () function allocates other space as needed, including the memory pointed to by gl_pathv.

The argument flags is used to modify the behavior of (). The value of flags is the bitwise inclusive OR of any of the following values defined in <glob.h>:

Append pathnames generated to the ones from a previous call (or calls) to glob(). The value of gl_pathc will be the total matches found by this call and the previous call(s). The pathnames are appended to, not merged with the pathnames returned by the previous call(s). Between calls, the caller must not change the setting of the GLOB_DOOFFS flag, nor change the value of gl_offs when GLOB_DOOFFS is set, nor (obviously) call globfree() for pglob.
Make use of the gl_offs field. If this flag is set, gl_offs is used to specify how many NULL pointers to prepend to the beginning of the gl_pathv field. In other words, gl_pathv will point to gl_offs NULL pointers, followed by gl_pathc pathname pointers, followed by a NULL pointer.
Causes glob() to return when it encounters a directory that it cannot open or read. Ordinarily, glob() continues to find matches.
Each pathname that is a directory that matches pattern has a slash appended.
If pattern does not match any pathname, then glob() returns a list consisting of only pattern, with the number of total pathnames set to 1, and the number of matched pathnames set to 0. The effect of backslash escaping is present in the pattern returned.
By default, a backslash (‘\’) character is used to escape the following character in the pattern, avoiding any special interpretation of the character. If GLOB_NOESCAPE is set, backslash escaping is disabled.
By default, the pathnames are sorted in ascending collation order; this flag prevents that sorting (speeding up glob()).

The following values may also be included in flags, however, they are non-standard extensions to IEEE Std 1003.2 (“POSIX.2”).

The following additional fields in the pglob structure have been initialized with alternate functions for glob to use to open, read, and close directories and to get stat information on names found in those directories. 
void *(*gl_opendir)(const char * name);
struct dirent *(*gl_readdir)(void *);
void (*gl_closedir)(void *);
int (*gl_lstat)(const char *name, struct stat *st);
int (*gl_stat)(const char *name, struct stat *st);

This extension is provided to allow programs such as restore(8) to provide globbing from directories stored on tape.

Pre-process the pattern string to expand ‘{pat,pat,...}’ strings like csh(1). The pattern ‘{}’ is left unexpanded for historical reasons (and csh(1) does the same thing to ease typing of find(1) patterns).
Set by the () function if the pattern included globbing characters. See the description of the usage of the gl_matchc structure member for more details.
Is the same as GLOB_NOCHECK but it only appends the pattern if it does not contain any of the special characters ``*'', ``?'' or ``[''. GLOB_NOMAGIC is provided to simplify implementing the historic csh(1) globbing behavior and should probably not be used anywhere else.
Expand patterns that start with ‘~’ to user name home directories.
Limit the total number of returned pathnames to the value provided in gl_matchc (default ARG_MAX). This option should be set for programs that can be coerced into a denial of service attack via patterns that expand to a very large number of matches, such as a long string of ‘*/../*/..’.

If, during the search, a directory is encountered that cannot be opened or read and errfunc is non-NULL, () calls (*errfunc)(path, errno). This may be unintuitive: a pattern like ‘*/Makefile’ will try to stat(2) ‘foo/Makefile’ even if ‘foo’ is not a directory, resulting in a call to errfunc. The error routine can suppress this action by testing for ENOENT and ENOTDIR; however, the GLOB_ERR flag will still cause an immediate return when this happens.

If errfunc returns non-zero, () stops the scan and returns GLOB_ABORTED after setting gl_pathc and gl_pathv to reflect any paths already matched. This also happens if an error is encountered and GLOB_ERR is set in flags, regardless of the return value of errfunc, if called. If GLOB_ERR is not set and either errfunc is NULL or errfunc returns zero, the error is ignored.

The () function is like glob() except that the error callback is a block pointer instead of a function pointer.

The () function frees any space associated with pglob from a previous call(s) to glob() or glob_b().

On successful completion, glob() and glob_b() return zero. In addition, the fields of pglob contain the values described below:

gl_pathc
contains the total number of matched pathnames so far. This includes other matches from previous invocations of glob() or glob_b() if GLOB_APPEND was specified.
gl_matchc
contains the number of matched pathnames in the current invocation of glob() or glob_b().
gl_flags
contains a copy of the flags argument with the bit GLOB_MAGCHAR set if pattern contained any of the special characters ``*'', ``?'' or ``['', cleared if not.
gl_pathv
contains a pointer to a NULL-terminated list of matched pathnames. However, if gl_pathc is zero, the contents of gl_pathv are undefined.

If glob() or glob_b() terminates due to an error, it sets errno and returns one of the following non-zero constants, which are defined in the include file <glob.h>:

An attempt to allocate memory failed, or if errno was E2BIG, GLOB_LIMIT was specified in the flags and pglob->gl_matchc or more patterns were matched.
The scan was stopped because an error was encountered and either GLOB_ERR was set or (*errfunc)() returned non-zero.
The pattern did not match a pathname and GLOB_NOCHECK was not set.

The arguments pglob->gl_pathc and pglob->gl_pathv are still set as specified above.

A rough equivalent of ‘ls -l *.c *.h’ can be obtained with the following code:

glob_t g;

g.gl_offs = 2;
glob("*.c", GLOB_DOOFFS, NULL, &g);
glob("*.h", GLOB_DOOFFS | GLOB_APPEND, NULL, &g);
g.gl_pathv[0] = "ls";
g.gl_pathv[1] = "-l";
execvp("ls", g.gl_pathv);

The glob() and glob_b() functions will not match filenames that begin with a period unless this is specifically requested (e.g., by ".*").

sh(1), fnmatch(3), regexp(3)

The current implementation of the glob() function conform to IEEE Std 1003.2 (“POSIX.2”). Collating symbol expressions, equivalence class expressions and character class expressions are not supported.

The flags GLOB_ALTDIRFUNC, GLOB_BRACE, GLOB_LIMIT, GLOB_MAGCHAR, GLOB_NOMAGIC, and GLOB_TILDE, and the fields gl_matchc and gl_flags are extensions to the POSIX standard and should not be used by applications striving for strict conformance.

The glob() and globfree() functions first appeared in 4.4BSD. The glob_b() function first appeared in Mac OS X 10.6.

Patterns longer than MAXPATHLEN may cause unchecked errors.

The glob() and glob_b() functions may fail and set errno for any of the errors specified for the library routines stat(2), closedir(3), opendir(3), readdir(3), malloc(3), and free(3).

June 11, 2017 Mac OS X 12