NAME

endutxent, getutxent, getutxid, getutxline, pututxline, setutxent — user accounting database functions

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <utmpx.h>

void
endutxent(void);

struct utmpx *
getutxent(void);

struct utmpx *
getutxid(const struct utmpx *id);

struct utmpx *
getutxline(const struct utmpx *line);

struct utmpx *
pututxline(const struct utmpx *utx);

void
setutxent(void);

DESCRIPTION

These functions provide access to the utmpx(5) user accounting database.

The getutxent() function reads the next entry from the database; if the database was not yet open, it also opens it. The setutxent() function resets the database, so that the next getutxent() call will get the first entry. The endutxent() function closes the database.

The getutxid() function returns the next entry of the type specified in its argument's ut_type field, or NULL if none is found. The getutxline() function returns the next LOGIN_PROCESS or USER_PROCESS entry which has the same name as specified in the ut_line field, or NULL if no match is found.

The pututxline() function adds the argument utmpx(5) entry line to the accounting database, replacing a previous entry for the same user if it exists. Only the superuser may write to the accounting database.

The utmpx structure

The utmpx structure has the following definition:

struct utmpx {
	char ut_user[_UTX_USERSIZE];	/* login name */
	char ut_id[_UTX_IDSIZE];	/* id */
	char ut_line[_UTX_LINESIZE];	/* tty name */
	pid_t ut_pid;			/* process id creating the entry */
	short ut_type;			/* type of this entry */
	struct timeval ut_tv;		/* time entry was created */
	char ut_host[_UTX_HOSTSIZE];	/* host name */
	__uint32_t ut_pad[16];		/* reserved for future use */
};

Valid entries for ut_type are:

BOOT_TIME: Time of a system boot.
DEAD_PROCESS: A session leader exited.
EMPTY: No valid user accounting information.
INIT_PROCESS: A process spawned by init(8).
LOGIN_PROCESS: The session leader of a logged-in user.
NEW_TIME: Time after system clock change.
OLD_TIME: Time before system clock change.
RUN_LVL: Run level. Provided for compatibility, not used.
USER_PROCESS: A user process.
SHUTDOWN_TIME: Time of system shutdown (extension to the standards).

For each value of ut_type, the other fields with meaningful values are as follows:

BOOT_TIME: ut_tv
DEAD_PROCESS: ut_id, ut_pid, ut_tv
EMPTY: (no others)
INIT_PROCESS: ut_id, ut_pid, ut_tv
LOGIN_PROCESS: ut_id, ut_user (implementation-defined name of the login process), ut_pid, ut_tv
NEW_TIME: ut_tv
OLD_TIME: ut_tv
RUN_LVL: (no used)
USER_PROCESS: ut_id, ut_user (login name of the user), ut_line, ut_pid, ut_host (hostname of remote user) ut_tv
SHUTDOWN_TIME: ut_tv

Other extensions to the standards

The ut_type value may also be OR-ed with the following masks:

UTMPX_AUTOFILL_MASK: Depending on the main part of ut_type value, other fields are automatically filled in (as specified in the meaningful fields table above). In particular, the ut_id field will be set using the convention of the last four characters of the ut_line field (itself filled in automatically from the tty name of the device connected to the standard input, output or error, whichever is available). Note that it is more efficient to fill in as many values as are already available beforehand, rather than have then automatically filled in.
UTMPX_DEAD_IF_CORRESPONDING_MASK: When ut_type value is DEAD_PROCESS, a call to pututxline() will succeed only if a corresponding entry already exists with a ut_type value of USER_PROCESS.

Note that the above mask values do not show up in any file format, or in any subsequent reads of the data.

To support wtmpx and lastlogx equivalent capability, pututxline() automatically writes to the appropriate files. Additional APIs to read these files is available in endutxent_wtmp(3) and getlastlogx(3).

Backward compatibility

Successful calls to pututxline() will automatically write equivalent entries into the utmp, wtmp and lastlog files. Programs that read these old files should work as expected. However, directly writing to these files does not make corresponding entries in utmpx and the wtmpx and lastlogx equivalent files, so such write-access is deprecated.

RETURN VALUES

The getutxent() function returns the next entry, or NULL on failure (end of database or problems reading from the database). The getutxid() and getutxline() functions return the matching structure on success, or NULL if no match was found.

The pututxline() function returns the structure that was successfully written, or NULL is returned and the global variable errno is set to indicate the error.

ERRORS

No errors are defined for the endutxent(), getutxent(), getutxid(), getutxline(), and setutxent() functions.

The pututxline() function may fail if:

[EPERM]: The process does not have appropriate privileges.
[EINVAL]: The UTMPX_DEAD_IF_CORRESPONDING_MASK flags was specified along with DEAD_PROCESS, but no corresponding entry with USER_PROCESS was found.

Other errors may be returned if UTMPX_AUTOFILL_MASK was specified, and a field could not be auto-filled.

STANDARDS

The endutxent(), getutxent(), getutxid(), getutxline(), pututxline(), setutxent() all conform to IEEE Std 1003.1-2001 (“POSIX.1”) (XSI extension), and previously to X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”). The fields ut_user, ut_id, ut_line, ut_pid, ut_type, and ut_tv conform to IEEE Std 1003.1-2001 (“POSIX.1”) (XSI extension), and previously to X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”).