updwtmp(3)                 Library Functions Manual                 updwtmp(3)

NAME
       updwtmp, logwtmp - append an entry to the wtmp file

LIBRARY
       System utilities library (libutil, -lutil)

SYNOPSIS
       #include <utmp.h>

       void updwtmp(const char *wtmp_file, const struct utmp *ut);
       void logwtmp(const char *line, const char *name, const char *host);

DESCRIPTION
       updwtmp() appends the utmp structure ut to the wtmp file.

       logwtmp() constructs a utmp structure using line, name, host, current
       time, and current process ID.  Then it calls updwtmp() to append the
       structure to the wtmp file.

FILES
       /var/log/wtmp
              database of past user logins

ATTRIBUTES
       For an explanation of the terms used in this section, see
       attributes(7).

       +---------------------------+---------------+--------------------------+
       |Interface                  | Attribute     | Value                    |
       +---------------------------+---------------+--------------------------+
       |updwtmp (), logwtmp ()     | Thread safety | MT-Unsafe sig:ALRM timer |
       +---------------------------+---------------+--------------------------+
VERSIONS
       For consistency with the other "utmpx" functions (see getutxent(3)),
       glibc provides (since glibc 2.1):

           #define _GNU_SOURCE          /* See feature_test_macros(7) */
           #include <utmpx.h>
           void updwtmpx (const char *wtmpx_file, const struct utmpx *utx);

       This function performs the same task as updwtmp(), but differs in that
       it takes a utmpx structure as its last argument.

STANDARDS
       None.

HISTORY
       Solaris, NetBSD.

SEE ALSO
       getutxent(3), wtmp(5)

Linux man-pages 6.7               2023-10-31                        updwtmp(3)