NAME

       gmtime, gmtime_r - convert a time value to a broken-down UTC time

SYNOPSIS

       #include <time.h>

       struct tm *gmtime(const time_t *timer);

       struct tm *gmtime_r(const time_t *restrict timer,
              struct tm *restrict result);

DESCRIPTION

       For  gmtime():    The  functionality  described on this reference page is aligned with the
       ISO C standard. Any conflict  between  the  requirements  described  here  and  the  ISO C
       standard  is  unintentional.  This  volume  of  IEEE Std 1003.1-2001  defers  to the ISO C
       standard.

       The gmtime() function shall convert the time in seconds since  the  Epoch  pointed  to  by
       timer into a broken-down time, expressed as Coordinated Universal Time (UTC).

       The relationship between a time in seconds since the Epoch used as an argument to gmtime()
       and the tm structure (defined in the <time.h> header) is  that  the  result  shall  be  as
       specified  in  the  expression given in the definition of seconds since the Epoch (see the
       Base Definitions volume of IEEE Std 1003.1-2001, Section 4.14, Seconds Since  the  Epoch),
       where the names in the structure and in the expression correspond.

       The same relationship shall apply for gmtime_r().

       The  gmtime()  function  need  not  be  reentrant.  A  function that is not required to be
       reentrant is not required to be thread-safe.

       The asctime(), ctime(), gmtime(), and localtime() functions shall return values in one  of
       two  static  objects: a broken-down time structure and an array of type char. Execution of
       any of the functions may overwrite the information returned in either of these objects  by
       any of the other functions.

       The  gmtime_r()  function  shall convert the time in seconds since the Epoch pointed to by
       timer into a broken-down time expressed as Coordinated Universal Time (UTC).  The  broken-
       down  time is stored in the structure referred to by result. The gmtime_r() function shall
       also return the address of the same structure.

RETURN VALUE

       Upon successful completion, the gmtime() function shall return a pointer to a  struct  tm.
       If an error is detected, gmtime() shall return a null pointer    and set errno to indicate
       the error.

       Upon successful completion, gmtime_r() shall return the address of the  structure  pointed
       to  by  the  argument  result.   If  an  error is detected, gmtime_r() shall return a null
       pointer.

ERRORS

       The gmtime() function shall fail if:

       EOVERFLOW
              The result cannot be represented.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The gmtime_r() function is thread-safe  and  returns  values  in  a  user-supplied  buffer
       instead of possibly using a static data area that may be overwritten by each call.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       asctime()  ,  clock()  ,  ctime()  ,  difftime()  ,  localtime() , mktime() , strftime() ,
       strptime() , time() , utime() ,  the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,
       <time.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .