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

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
       daylight, timezone, tzname, tzset - set timezone conversion information
SYNOPSIS
       #include <time.h>

       extern int daylight;
       extern long timezone;

       extern char *tzname[2];
       void tzset(void);

DESCRIPTION
       The tzset() function shall use the value of the environment variable TZ
       to  set  time  conversion  information  used  by  ctime(), localtime(),
       mktime(), and strftime() . If TZ is absent from the environment, imple-
       mentation-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
       IEEE Std 1003.1-2001, 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 Univer-
       sal Time (UTC) and local standard time.
RETURN VALUE
       The tzset() function shall not return a value.
ERRORS
       No errors are defined.
       The following sections are informative.
EXAMPLES
       Example TZ variables and their timezone differences are  given  in  the
       table below:
                                TZ          timezone
                                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
       None.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       ctime(), localtime(), mktime(), strftime(), the Base Definitions volume
       of IEEE Std 1003.1-2001, Chapter 8, Environment Variables, <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 .

IEEE/The Open Group                  2003                            TZSET(3P)