71 lines
1.6 KiB
Groff
71 lines
1.6 KiB
Groff
.TH UTMP 5
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.SH NAME
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utmp, wtmp \- logged in users, login and logout history
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.SH SYNOPSIS
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.nf
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.ft B
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#include <sys/types.h>
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#include <utmp.h>
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.SH DESCRIPTION
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.de SP
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.if t .sp 0.4
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.if n .sp
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..
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The files
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.B /etc/utmp
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and
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.B /usr/adm/wtmp
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respectively contain the currently logged in users, and the history of
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logins and logouts.
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.PP
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Each file is an array of the following structure defined in <utmp.h>:
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.PP
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.nf
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.ta +5n +15n +15n
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struct utmp {
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char ut_user[8]; /* user name */
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char ut_line[12]; /* terminal name */
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char ut_host[16]; /* host name, when remote */
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time_t ut_time; /* login/logout time */
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};
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.SP
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.ta +15n
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#define ut_name ut_user /* for compatibility with other systems */
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.fi
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.DT
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.PP
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The structure contains more fields than those listed, but they are only of
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interest to
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.B init
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and
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.BR login .
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Note that the
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.B ut_name
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field is a compatibility alias for
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.BR ut_user ,
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it is actually better to use it.
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.PP
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A login entry is completely specified. A logout entry has a null string for
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.BR ut_name .
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A shutdown or reboot entry has an
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.B ut_line
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field containing a "~" (tilde). The
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.B ut_name
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field is usually the name of the program that did the shutdown, or "reboot"
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at reboot. This is a bit confusing, but note that there should always be
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two such entries. If you see just one entry then the system has crashed, if
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you see two entries then the system was properly shut down and later
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rebooted.
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.SH FILES
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.TP 25n
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.B /etc/utmp
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Currently logged in users.
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.TP
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.B /usr/adm/wtmp
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History of logins and logouts.
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.SH "SEE ALSO"
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.BR who (1),
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.BR ttyslot (3).
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.SH AUTHOR
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Kees J. Bot (kjb@cs.vu.nl)
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