timegm

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

DESCRIPTION
       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
       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
       EOVERFLOW
              The result cannot be represented.

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

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

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

COLOPHON
       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)