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UPDWTMP(3) Linux Programmer's Manual UPDWTMP(3)
updwtmp, logwtmp - append an entry to the wtmp file
#include <utmp.h>
void updwtmp(const char *wtmp_file, const struct utmp *ut);
void logwtmp(const char *line, const char *name, const char *host);
updwtmp() appends the utmp structure ut to the wtmp file.
logwtmp() constructs a utmp structure using line, name, host, current time and
current process ID. Then it calls updwtmp() to append the structure to the
wtmp file.
/var/log/wtmp
database of past user logins
Not in POSIX.1-2001. Present on Solaris, NetBSD, and perhaps other systems.
Both functions are available under glibc2, but not under libc5. However,
logwtmp() used to occur in the old libbsd. These days, the logwtmp() function
is included in libutil. (Hence you'll need to add -lutil to your compiler
command line to get it.)
For consistency with the other "utmpx" functions (see getutxent(3)), glibc
provides (since version 2.1):
#include <utmpx.h>
void updwtmpx (const char *wtmpx_file, const struct utmpx *utx);
This function performs the same task as updwtmp(), but differs in that it
takes a utmpx structure as its last argument.
getutxent(3), wtmp(5)
This page is part of release 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
GNU 2008-07-02 UPDWTMP(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface