PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

GMTIME(3P)                POSIX Programmer's Manual               GMTIME(3P)

PROLOG         top

       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         top

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

SYNOPSIS         top

       #include <time.h>

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

DESCRIPTION         top

       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         top

       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         top

       The gmtime() and gmtime_r() functions shall fail if:

       EOVERFLOW
              The result cannot be represented.

       The following sections are informative.

EXAMPLES         top

       None.

APPLICATION USAGE         top

       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         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       asctime(3p), clock(3p), ctime(3p), difftime(3p), localtime(3p),
       mktime(3p), strftime(3p), strptime(3p), time(3p), utime(3p)

       The Base Definitions volume of POSIX.1‐2008, Section 4.15, Seconds
       Since the Epoch, time.h(0p)

COPYRIGHT         top

       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 .

IEEE/The Open Group                 2013                          GMTIME(3P)