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

NAME
       timegm, timelocal - inverses of gmtime and localtime

SYNOPSIS
       #include 

       timet timelocal(struct tm *tm);

       timet timegm(struct tm *tm);

   Feature Test Macro Requirements for glibc (see featuretestmacros(7)):

       timelocal(), timegm(): BSDSOURCE || SVIDSOURCE

DESCRIPTION
       The functions timelocal() and timegm() are the inverses of localtime(3)
       and gmtime(3).

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; see NOTES.

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

           #include 
           #include 

           timet
           mytimegm(struct tm *tm)
           {
               timet ret;
               char *tz;

               tz = getenv("TZ");
               if (tz)
                   tz = strdup(tz);
               setenv("TZ", "", 1);
               tzset();
               ret = mktime(tm);
               if (tz) {
                   setenv("TZ", tz, 1);
                   free(tz);
               } else
                   unsetenv("TZ");
               tzset();
               return ret;
           }

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

COLOPHON
       This page is part of release 3.53 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                               2013-07-04                         TIMEGM(3)