TIMEGM(3) Linux Programmer's Manual TIMEGM(3)
NAME
timegm, timelocal - inverses of gmtime and localtime
SYNOPSIS
#include <time.h>
time_t timelocal(struct tm *tm);
time_t timegm(struct tm *tm);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
timelocal(), timegm(): _BSD_SOURCE || _SVID_SOURCE
DESCRIPTION
The functions timelocal() and timegm() are the inverses of localtime(3)
and gmtime(3).
CONFORMING TO
These functions are nonstandard GNU extensions that are also present on
the BSDs. Avoid their use; see NOTES.
NOTES
The timelocal() function is equivalent to the POSIX standard function
mktime(3). There is no reason to ever use it.
For a portable version of timegm(), set the TZ environment variable to
UTC, call mktime(3) and restore the value of TZ. Something like
#include <time.h>
#include <stdlib.h>
time_t
my_timegm(struct tm *tm)
{
time_t ret;
char *tz;
tz = getenv("TZ");
if (tz)
tz = strdup(tz);
setenv("TZ", "", 1);
tzset();
ret = mktime(tm);
if (tz) {
setenv("TZ", tz, 1);
free(tz);
} else
unsetenv("TZ");
tzset();
return ret;
}
SEE ALSO
gmtime(3), localtime(3), mktime(3), tzset(3)
COLOPHON
This page is part of release 3.53 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 2013-07-04 TIMEGM(3)