PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

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
       POSIX.1‐2008 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  POSIX.1‐2008,
       Section  4.15,  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 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 and set errno to
       indicate the error.

ERRORS

       The gmtime() and gmtime_r() functions 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 POSIX.1‐2008, Section 4.15, Seconds Since the Epoch, <time.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications  Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
       and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .