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'\" t
.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.TH updwtmp 3 2025-05-17 "Linux man-pages (unreleased)"
.SH NAME
updwtmp, logwtmp \- append an entry to the wtmp file
.SH LIBRARY
System utilities library
.RI ( libutil ,\~ \-lutil )
.SH SYNOPSIS
.nf
.B #include <utmp.h>
.P
.BI "void updwtmp(const char *" wtmp_path ", const struct utmp *" ut );
.BI "void logwtmp(const char *" line ", const char *" name \
", const char *" host );
.fi
.SH DESCRIPTION
.BR updwtmp ()
appends the utmp structure
.I ut
to the wtmp file.
.P
.BR logwtmp ()
constructs a utmp structure using
.IR line ", " name ", " host ,
current time, and current process ID.
Then it calls
.BR updwtmp ()
to append the structure to the wtmp file.
.SH FILES
.TP
.I /var/log/wtmp
database of past user logins
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface Attribute Value
T{
.na
.nh
.BR updwtmp (),
.BR logwtmp ()
T} Thread safety MT-Unsafe sig:ALRM timer
.TE
.SH VERSIONS
For consistency with the other "utmpx" functions (see
.BR getutxent (3)),
glibc provides (since glibc 2.1):
.P
.in +4n
.EX
.BR "#define _GNU_SOURCE " "/* See feature_test_macros(7) */"
.B #include <utmpx.h>
.BI "void updwtmpx (const char *" wtmpx_path ", const struct utmpx *" utx );
.EE
.in
.P
This function performs the same task as
.BR updwtmp (),
but differs in that it takes a
.I utmpx
structure as its last argument.
.SH STANDARDS
None.
.SH HISTORY
Solaris, NetBSD.
.SH SEE ALSO
.BR getutxent (3),
.BR wtmp (5)
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