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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 4.09 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/.



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