.\" Copyright 1997 Nicolás Lichtmaier <nick@debian.org>
.\" Created Wed Jul  2 23:27:34 ART 1997
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.\" Added info on availability, aeb, 971207
.\" Added -lutil remark, 030718
.\" 2008-07-02, mtk, document updwtmpx()
.\"
.TH UPDWTMP 3  2021-03-22 "GNU" "Linux Programmer's Manual"
.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>
.PP
.BI "void updwtmp(const char *" wtmp_file ", 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.
.PP
.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).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR updwtmp (),
.BR logwtmp ()
T}	Thread safety	MT-Unsafe sig:ALRM timer
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
Not in POSIX.1.
Present on Solaris, NetBSD, and perhaps other systems.
.SH NOTES
For consistency with the other "utmpx" functions (see
.BR getutxent (3)),
glibc provides (since version 2.1):
.PP
.in +4n
.EX
.B #include <utmpx.h>
.BI "void updwtmpx (const char *" wtmpx_file ", const struct utmpx *" utx );
.EE
.in
.PP
This function performs the same task as
.BR updwtmp (),
but differs in that it takes a
.I utmpx
structure as its last argument.
.SH SEE ALSO
.BR getutxent (3),
.BR wtmp (5)