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

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

       daylight, timezone, tzname, tzset — set timezone conversion
       information

SYNOPSIS         top

       #include <time.h>

       extern int daylight;
       extern long timezone;
       extern char *tzname[2];
       void tzset(void);

DESCRIPTION         top

       The tzset() function shall use the value of the environment variable
       TZ to set time conversion information used by ctime(3p),
       localtime(3p), mktime(3p), and strftime(3p).  If TZ is absent from
       the environment, implementation-defined default timezone information
       shall be used.

       The tzset() function shall set the external variable tzname as
       follows:

           tzname[0] = "std";
           tzname[1] = "dst";

       where std and dst are as described in the Base Definitions volume of
       POSIX.1‐2008, Chapter 8, Environment Variables.

       The tzset() function also shall set the external variable daylight to
       0 if Daylight Savings Time conversions should never be applied for
       the timezone in use; otherwise, non-zero. The external variable
       timezone shall be set to the difference, in seconds, between
       Coordinated Universal Time (UTC) and local standard time.

RETURN VALUE         top

       The tzset() function shall not return a value.

ERRORS         top

       No errors are defined.

       The following sections are informative.

EXAMPLES         top

       Example TZ variables and their timezone differences are given in the
       table below:

                             ┌───────────┬────────────┐
                             │    TZtimezone  │
                             ├───────────┼────────────┤
                             │EST5EDT    │ 5*60*60    │
                             │GMT0       │ 0*60*60    │
                             │JST-9      │ −9*60*60   │
                             │MET-1MEST  │ −1*60*60   │
                             │MST7MDT    │ 7*60*60    │
                             │PST8PDT    │ 8*60*60    │
                             └───────────┴────────────┘

APPLICATION USAGE         top

       None.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       ctime(3p), localtime(3p), mktime(3p), strftime(3p)

       The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
       Variables, 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                           TZSET(3P)

Pages that refer to this page: time.h(0p)daylight(3p)localtime(3p)mktime(3p)strftime(3p)timezone(3p)