updwtmp(3) Library Functions Manual updwtmp(3)

updwtmp, logwtmp - append an entry to the wtmp file

System utilities library (libutil, -lutil)

#include <utmp.h>
void updwtmp(const char *wtmp_file, const struct utmp *ut);
void logwtmp(const char *line, const char *name, const char *host);

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.

database of past user logins

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

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.


Solaris, NetBSD.

getutxent(3), wtmp(5)

2024-05-02 Linux man-pages 6.9.1