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.

/var/log/wtmp
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.

None.

Solaris, NetBSD.

getutxent(3), wtmp(5)

2024-05-02 Linux man-pages 6.8