'\" et

.TH TZSET "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"

.SH 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.

.SH NAME

daylight,

timezone,

tzname,

tzset

\(em set timezone conversion information

.SH SYNOPSIS

.LP

.nf

#include <time.h>

.P

extern int daylight;

extern long timezone;

extern char *tzname[2];

void tzset(void);

.fi

.SH DESCRIPTION

The

\fItzset\fR()

function shall use the value of the environment variable

.IR TZ

to set time conversion information used by

.IR "\fIctime\fR\^(\|)",

.IR "\fIlocaltime\fR\^(\|)",

.IR "\fImktime\fR\^(\|)",

and

.IR "\fIstrftime\fR\^(\|)".

If

.IR TZ

is absent from the environment, implementation-defined default

timezone information shall be used.

.P

The

\fItzset\fR()

function shall set the external variable

.IR tzname

as follows:

.sp

.RS 4

.nf

\fB

tzname[0] = "\fIstd\fP";

tzname[1] = "\fIdst\fP";

.fi \fR

.P

.RE

.P

where

.IR std

and

.IR dst

are as described in the Base Definitions volume of POSIX.1\(hy2008,

.IR "Chapter 8" ", " "Environment Variables".

.P

The

\fItzset\fR()

function also shall set the external variable

.IR daylight

to 0 if Daylight Savings Time conversions should never be applied for

the timezone in use; otherwise, non-zero. The external variable

.IR timezone

shall be set to the difference, in seconds, between Coordinated

Universal Time (UTC) and local standard time.

.SH "RETURN VALUE"

The

\fItzset\fR()

function shall not return a value.

.SH ERRORS

No errors are defined.

.LP

.IR "The following sections are informative."

.SH EXAMPLES

Example

.IR TZ

variables and their timezone differences are given in the table below:

.TS

center box tab(!);

cI | cI

lw(1i) | lw(1i).

TZ!timezone

_

EST5EDT!5*60*60

GMT0!0*60*60

JST-9!\(mi9*60*60

MET-1MEST!\(mi1*60*60

MST7MDT!7*60*60

PST8PDT!8*60*60

.TE

.SH "APPLICATION USAGE"

None.

.SH RATIONALE

None.

.SH "FUTURE DIRECTIONS"

None.

.SH "SEE ALSO"

.IR "\fIctime\fR\^(\|)",

.IR "\fIlocaltime\fR\^(\|)",

.IR "\fImktime\fR\^(\|)",

.IR "\fIstrftime\fR\^(\|)"

.P

The Base Definitions volume of POSIX.1\(hy2008,

.IR "Chapter 8" ", " "Environment Variables",

.IR "\fB<time.h>\fP"

.SH COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form

from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology

-- Portable Operating System Interface (POSIX), The Open Group Base

Specifications Issue 7, Copyright (C) 2013 by the Institute of

Electrical and Electronics Engineers, Inc and The Open Group.

(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

Any typographical or formatting errors that appear

in this page are most likely

to have been introduced during the conversion of the source files to

man page format. To report such errors, see

https://www.kernel.org/doc/man-pages/reporting_bugs.html .