UTMPX(5)

NAME
utmpx, wtmpx, lastlogx - user accounting database

SYNOPSIS
#include <utmpx.h>

DESCRIPTION
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 files are not automatically created if they do not exist; they must be created manually.

The interface to the utmpx file is described in endutxent(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), endutxent(3), logwtmpx(3), ac(8), init(8), newsyslog(8), reboot(8)