Mac Developer Library Developer


This manual page is part of Xcode Tools version 5.0

To obtain these tools:

If you are running a version of Xcode Tools other than 5.0, view the documentation locally:

  • In Xcode

  • In Terminal, using the man(1) command

Reading manual pages

Manual pages are intended as a quick reference for people who already understand a technology.

  • To learn how the manual is organized or to learn about command syntax, read the manual page for manpages(5).

  • For more information about this technology, look for other documentation in the Apple Developer Library.

  • For general information about writing shell scripts, read Shell Scripting Primer.

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

       timegm, timelocal - inverses for gmtime and localtime

       #include <time.h>

       time_t timelocal (struct tm *tm);

       time_t timegm (struct tm *tm);

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

       These  functions  are  GNU  extensions.  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() and restore
       the value of TZ.  Something like

              #include <time.h>
              #include <stdlib.h>

              time_t my_timegm (struct tm *tm) {
                  time_t ret;
                  char *tz;

                  tz = getenv("TZ");
                  setenv("TZ", "", 1);
                  ret = mktime(tm);
                  if (tz)
                      setenv("TZ", tz, 1);
                  return ret;

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

GNU                                              2001-12-26                                        TIMEGM(3)

Reporting Problems

The way to report a problem with this manual page depends on the type of problem:

Content errors
Report errors in the content of this documentation with the feedback links below.
Bug reports
Report bugs in the functionality of the described tool or API through Bug Reporter.
Formatting problems
Report formatting mistakes in the online version of these pages with the feedback links below.