TIMEGM(3) Linux Programmers Manual TIMEGM(3)
timegm, timelocal - inverses of gmtime and localtime
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
The functions timelocal() and timegm() are the inverses of localtime(3)
These functions are non-standard GNU extensions that are also present
on the BSDs. Avoid their use; see 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
my_timegm(struct tm *tm)
tz = getenv("TZ");
setenv("TZ", "", 1);
ret = mktime(tm);
setenv("TZ", tz, 1);
gmtime(3), localtime(3), mktime(3), tzset(3)
This page is part of release 3.05 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 2007-07-26 TIMEGM(3)