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/.