1TIMEGM(3)                  Linux Programmer's Manual                 TIMEGM(3)
2
3
4

NAME

6       timegm, timelocal - inverses of gmtime and localtime
7

SYNOPSIS

9       #include <time.h>
10
11       time_t timelocal(struct tm *tm);
12
13       time_t timegm(struct tm *tm);
14
15   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
16
17       timelocal(), timegm(): _BSD_SOURCE || _SVID_SOURCE
18

DESCRIPTION

20       The functions timelocal() and timegm() are the inverses of localtime(3)
21       and gmtime(3).
22

CONFORMING TO

24       These functions are nonstandard GNU extensions that are also present on
25       the BSDs.  Avoid their use; see NOTES.
26

NOTES

28       The  timelocal()  function is equivalent to the POSIX standard function
29       mktime(3).  There is no reason to ever use it.
30
31       For a portable version of timegm(), set the TZ environment variable  to
32       UTC, call mktime(3) and restore the value of TZ.  Something like
33
34           #include <time.h>
35           #include <stdlib.h>
36
37           time_t
38           my_timegm(struct tm *tm)
39           {
40               time_t ret;
41               char *tz;
42
43               tz = getenv("TZ");
44               if (tz)
45                   tz = strdup(tz);
46               setenv("TZ", "", 1);
47               tzset();
48               ret = mktime(tm);
49               if (tz) {
50                   setenv("TZ", tz, 1);
51                   free(tz);
52               } else
53                   unsetenv("TZ");
54               tzset();
55               return ret;
56           }
57

SEE ALSO

59       gmtime(3), localtime(3), mktime(3), tzset(3)
60

COLOPHON

62       This  page  is  part of release 3.53 of the Linux man-pages project.  A
63       description of the project, and information about reporting  bugs,  can
64       be found at http://www.kernel.org/doc/man-pages/.
65
66
67
68GNU                               2013-07-04                         TIMEGM(3)