TZSET(P) POSIX Programmer's Manual TZSET(P)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 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 ALSOctime() , 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(P)
