.\" Copyright (c) 1993 Michael Haardt (michael@cantor.informatik.rwth-aachen.de),
.\" Fri Apr 2 11:32:09 MET DST 1993
.\"
+.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public
-.\" License along with this manual; if not, write to the Free
-.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
-.\" USA.
+.\" License along with this manual; if not, see
+.\" <http://www.gnu.org/licenses/>.
+.\" %%%LICENSE_END
.\"
.\" Modified 1993-07-25 by Rik Faith (faith@cs.unc.edu)
.\" Modified 1995-02-26 by Michael Haardt
.\" Modified 1996-07-20 by Michael Haardt
-.\" Modified 1997-07-02 by Nicolás Lichtmaier <nick@debian.org>
+.\" Modified 1997-07-02 by Nicolás Lichtmaier <nick@debian.org>
.\" Modified 2004-10-31 by aeb, following Gwenole Beauchesne
-.TH UTMP 5 2013-02-11 "Linux" "Linux Programmer's Manual"
+.TH UTMP 5 2017-09-15 "Linux" "Linux Programmer's Manual"
.SH NAME
utmp, wtmp \- login records
.SH SYNOPSIS
.IR <utmp.h>
(note that this is only one of several definitions
around; details depend on the version of libc):
+.PP
.in +4n
-.nf
-.sp
+.EX
/* Values for ut_type field, below */
#define EMPTY 0 /* Record does not contain valid info
messages */
struct exit_status ut_exit; /* Exit status of a process
marked as DEAD_PROCESS; not
- used by Linux init(8) */
+ used by Linux init (1 */
/* The ut_session and ut_tv fields must be the same size when
compiled 32- and 64-bit. This allows data files and shared
memory to be shared between 32- and 64-bit applications. */
#endif
#define ut_xtime ut_tv.tv_sec
#define ut_addr ut_addr_v6[0]
-.sp
-.fi
+.EE
.in
+.PP
This structure gives the name of the special file associated with the
user's terminal, the user's login name, and the time of login in the form
of
of the field.
.PP
The first entries ever created result from
-.BR init (8)
+.BR init (1)
processing
.BR inittab (5).
Before an entry is processed, though,
-.BR init (8)
+.BR init (1)
cleans up utmp by setting \fIut_type\fP to \fBDEAD_PROCESS\fP, clearing
\fIut_user\fP, \fIut_host\fP, and \fIut_time\fP with null bytes for each
record which \fIut_type\fP is not \fBDEAD_PROCESS\fP or \fBRUN_LVL\fP
and where no process with PID \fIut_pid\fP exists.
If no empty record
with the needed \fIut_id\fP can be found,
-.BR init (8)
+.BR init (1)
creates a new one.
It sets \fIut_id\fP from the inittab, \fIut_pid\fP and \fIut_time\fP to the
current values, and \fIut_type\fP to \fBINIT_PROCESS\fP.
\fIut_line\fP instead of the preferable \fIut_pid\fP.
.PP
When
-.BR init (8)
+.BR init (1)
finds that a process has exited, it locates its utmp
entry by \fIut_pid\fP, sets \fIut_type\fP to \fBDEAD_PROCESS\fP, and
clears \fIut_user\fP, \fIut_host\fP and \fIut_time\fP with null bytes.
changes it.
\fIwtmp\fP is maintained by
.BR login (1),
-.BR init (8),
+.BR init (1),
and some versions of
.BR getty (8)
(e.g.,
None of these programs creates the file, so if it is
removed, record-keeping is turned off.
.SH FILES
-/var/run/utmp
+.I /var/run/utmp
.br
-/var/log/wtmp
-.SH "CONFORMING TO"
+.I /var/log/wtmp
+.SH CONFORMING TO
.PP
POSIX.1 does not specify a
.I utmp
and
.I ut_user
fields.
-
+.PP
Linux defines the
.I utmpx
structure to be the same as the
.I utmp
structure.
-.SS Comparison with Historical Systems
+.SS Comparison with historical systems
Linux utmp entries conform neither to v7/BSD nor to System V; they are a
mix of the two.
-
+.PP
v7/BSD has fewer fields; most importantly it lacks
\fIut_type\fP, which causes native v7/BSD-like programs to display (for
example) dead or login entries.
Further, there is no configuration file
which allocates slots to sessions.
BSD does so because it lacks \fIut_id\fP fields.
-
+.PP
In Linux (as in System V), the \fIut_id\fP field of a
record will never change once it has been set, which reserves that slot
without needing a configuration file.
systems, where utmp logging can be disabled by removing the file, utmp
must always exist on Linux.
If you want to disable
-.BR who (1)
+.BR who (1),
then do not make utmp world readable.
.PP
The file format is machine-dependent, so it is recommended that it be
.IR tv_usec .
Since \fIut_tv\fP may not be the same as \fIstruct timeval\fP,
then instead of the call:
+.PP
.in +4n
-.nf
-.sp
+.EX
gettimeofday((struct timeval *) &ut.ut_tv, NULL);
-.fi
+.EE
.in
-
+.PP
the following method of setting this field is recommended:
+.PP
.in +4n
-.nf
-.sp
+.EX
struct utmp ut;
struct timeval tv;
gettimeofday(&tv, NULL);
ut.ut_tv.tv_sec = tv.tv_sec;
ut.ut_tv.tv_usec = tv.tv_usec;
-.fi
+.EE
.in
-.PP
-Note that the \fIutmp\fP struct from libc5 has changed in libc6.
-Because of this,
-binaries using the old libc5 struct will corrupt
-.IR /var/run/utmp " and/or " /var/log/wtmp .
-.SH BUGS
-This man page is based on the libc5 one, things may work differently now.
-.SH "SEE ALSO"
+.\" .PP
+.\" Note that the \fIutmp\fP struct from libc5 has changed in libc6.
+.\" Because of this,
+.\" binaries using the old libc5 struct will corrupt
+.\" .IR /var/run/utmp " and/or " /var/log/wtmp .
+.\" .SH BUGS
+.\" This man page is based on the libc5 one, things may work differently now.
+.SH SEE ALSO
.BR ac (1),
.BR date (1),
+.BR init (1),
.BR last (1),
.BR login (1),
+.BR logname (1),
+.BR lslogins (1),
+.BR users (1),
.BR utmpdump (1),
.BR who (1),
.BR getutent (3),
.BR login (3),
.BR logout (3),
.BR logwtmp (3),
-.BR updwtmp (3),
-.BR init (8)
+.BR updwtmp (3)
projects / thirdparty / man-pages.git / blobdiff