UTMP(5) — UNIX Programmer’s Manual
NAME
utmp, wtmp − login records
SYNOPSIS
#include <utmp.h>
DESCRIPTION
The utmp file allows one to discover information about who is currently using UNIX. The file is a sequence of entries with the following structure declared in the include file:
/∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗ ∗∗∗∗∗∗∗∗∗∗∗∗∗
Copyright 1982
VALID LOGIC SYSTEMS INCORPORATED
This listing contains confidential proprietary information which is not to
be disclosed to unauthorized persons without written consent of an officer
of Valid Logic Systems Incorporated.
The copyright notice appearing above is included to provide statutory
protection in the event of unauthorized or unintentional public disclosure.
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struct utmp {
charut_line[8];/∗ tty name ∗/
charut_name[8];/∗ user id ∗/
longut_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 all 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 terminal names ‘|’ and ‘}’ indicate the system-maintained time just before and just after a date command has changed the system’s idea of the time.
Wtmp is maintained by login(1) 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
/etc/utmp
/usr/adm/wtmp
SEE ALSO
login(1), init(8), who(1), ac(8)
4th Berkeley Distribution — %W%%Q%%Y%