UTMPX(5)

NAME
utmpx, wtmpx, lastlogx - user accounting database

SYNOPSIS
#include <utmpx.h>

DESCRIPTION
In contrast to the formerly used legacy utmp and wtmp, the extended databases in utmpx and wtmpx reserve more space for logging hostnames, and also information on a process' ID, termination signal and exit status.

The <utmpx.h> header defines the structures and functions for logging user. Currently logged in users are tracked in /var/run/utmpx, a list of all logins and logouts, as well as all shutdowns, reboots and date changes, is kept in /var/log/wtmpx, and the last login of each user is noted in /var/log/lastlogx.

The interface to the utmpx file is described in getutxent(3).

The wtmpx file can grow rapidly on busy systems, and is normally rotated with newsyslog(8).

In the event of a date change, a shutdown, or a reboot, the following items are logged in the wtmpx file:
date
    The system time has been manually or automatically updated by date(1). The command name date is recorded in the field ut_name. In the field ut_line, the character ‘\*(Ba’ indicates the time prior to the change, and the character ‘{’ indicates the new time.
reboot
shutdown
    A system reboot or shutdown has been initiated. The character ‘~’ is placed in the field ut_line, and reboot or shutdown in the field ut_name (see shutdown(8) and reboot(8)), using logwtmpx(3).

FILES
/var/run/utmpx
    The utmpx file.
/var/log/wtmpx
    The wtmpx file.
/var/log/lastlogx
    The lastlogx file.

SEE ALSO
last(1), login(1), rwho(1), w(1), who(1), wtmpcvt(1), endutxent(3), logwtmpx(3), ac(8), init(8), newsyslog(8), reboot(8)