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 correspond-
       ing 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, 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 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
       Universal 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 Technol-
       ogy -- 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)