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Command: utmp | Section: 5 | Source: UNIX v10 | File: utmp.5
UTMP(5) File Formats Manual UTMP(5)
NAME
utmp, wtmp - login records
SYNOPSIS
#include <utmp.h>
DESCRIPTION
The utmp file allows one to discover information about who is currently
logged in. The file is a sequence of entries with the following struc-
ture declared in the include file:
struct utmp {
char ut_line[8]; /* tty name */
char ut_name[8]; /* user id */
long ut_time; /* time on */
};
This structure gives the name of the special file associated with the
user's terminal, the user's login name, and the time of the login in
the form of time(2).
The wtmp file records logins and logouts. Its format is exactly like
utmp except that a null user name indicates a logout on the associated
terminal. Furthermore, the terminal name indicates that the system was
rebooted at the indicated time; the adjacent pair of entries with ter-
minal names and indicate the system-maintained time just before and
just after a date(1) command changed the system's idea of the time.
Wtmp is maintained by login(8) and init(8). Neither of these programs
creates the file, so if it is removed record-keeping is turned off. It
is summarized by ac(8).
FILES
SEE ALSO
login(8), init(8), who(1), ac(8)
UTMP(5)