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)