man tzset () - set timezone conversion information

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:
center; l l.
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 .