updwtmp(3) - BetterMan

updwtmp(3)

append an entry to the wtmp file

distropkg manpages-dev@6.9.1-1dataset 2026-04-01T06:19:02Z+debian+ec4110e+mandoc:1.14.6-4

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
);

—

Options · 1

/var/log/wtmp

database of past user logins

NAME

updwtmp, logwtmp - append an entry to the wtmp file

LIBRARY

System utilities library (libutil, -lutil)

SYNOPSIS

bash

#include <utmp.h>

bash

void updwtmp(const char *\nwtmp_file\n, const struct utmp *\nut\n);\n
\nvoid logwtmp(const char *\nline\n, const char *\nname\n, const char *\nhost\n);

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):

bash

#define _GNU_SOURCE          \n/* See feature_test_macros(7) */
\n#include <utmpx.h>\n
\nvoid updwtmpx (const char *\nwtmpx_file\n, const struct utmpx *\nutx\n);\n

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.