timegm(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

TIMEGM(3)               Linux Programmer's Manual              TIMEGM(3)

NAME         top

       timegm, timelocal - inverses of gmtime and localtime

SYNOPSIS         top

       #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():
           Since glibc 2.19:
               _DEFAULT_SOURCE
           Glibc 2.19 and earlier:
               _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

       The functions timelocal() and timegm() are the inverses of
       localtime(3) and gmtime(3).  Both functions take a broken-down
       time and convert it to calendar time (seconds since the Epoch,
       1970-01-01 00:00:00 +0000, UTC).  The difference between the two
       functions is that timelocal() takes the local timezone into
       account when doing the conversion, while timegm() takes the input
       value to be Coordinated Universal Time (UTC).

RETURN VALUE         top

       On success, these functions return the calendar time (seconds
       since the Epoch), expressed as a value of type time_t.  On error,
       they return the value (time_t) -1 and set errno to indicate the
       cause of the error.

ERRORS         top

       EOVERFLOW
              The result cannot be represented.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────────────────┬───────────────┬────────────────────┐
       │Interface             Attribute     Value              │
       ├──────────────────────┼───────────────┼────────────────────┤
       │timelocal(), timegm() │ Thread safety │ MT-Safe env locale │
       └──────────────────────┴───────────────┴────────────────────┘

CONFORMING TO         top

       These functions are nonstandard GNU extensions that are also
       present on the BSDs.  Avoid their use.

NOTES         top

       The timelocal() function is equivalent to the POSIX standard
       function mktime(3).  There is no reason to ever use it.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.10 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

GNU                            2016-12-12                      TIMEGM(3)

Pages that refer to this page: ctime(3)