+++ /dev/null
-.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
-.\"
-.\" %%%LICENSE_START(VERBATIM)
-.\" Permission is granted to make and distribute verbatim copies of this
-.\" manual provided the copyright notice and this permission notice are
-.\" preserved on all copies.
-.\"
-.\" Permission is granted to copy and distribute modified versions of this
-.\" manual under the conditions for verbatim copying, provided that the
-.\" entire resulting derived work is distributed under the terms of a
-.\" permission notice identical to this one.
-.\"
-.\" Since the Linux kernel and libraries are constantly changing, this
-.\" manual page may be incorrect or out-of-date. The author(s) assume no
-.\" responsibility for errors or omissions, or for damages resulting from
-.\" the use of the information contained herein. The author(s) may not
-.\" have taken the same level of care in the production of this manual,
-.\" which is licensed free of charge, as they might when working
-.\" professionally.
-.\"
-.\" Formatted or processed versions of this manual, if unaccompanied by
-.\" the source, must acknowledge the copyright and authors of this work.
-.\" %%%LICENSE_END
-.\"
-.\" References consulted:
-.\" Linux libc source code
-.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
-.\" 386BSD man pages
-.\" Modified Sun Jul 25 11:01:58 1993 by Rik Faith (faith@cs.unc.edu)
-.\" Modified 2001-11-13, aeb
-.\" Modified 2004-12-01 mtk and Martin Schulze <joey@infodrom.org>
-.\"
-.TH TZSET 3 2015-01-30 "" "Linux Programmer's Manual"
-.SH NAME
-tzset, tzname, timezone, daylight \- initialize time conversion information
-.SH SYNOPSIS
-.nf
-.B #include <time.h>
-.sp
-.B void tzset (void);
-.sp
-.BI "extern char *" tzname [2];
-.BI "extern long " timezone ;
-.BI "extern int " daylight ;
-.fi
-.sp
-.in -4n
-Feature Test Macro Requirements for glibc (see
-.BR feature_test_macros (7)):
-.in
-.sp
-.BR tzset ():
-_POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE || _POSIX_SOURCE
-.br
-.IR tzname :
-_POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE || _POSIX_SOURCE
-.br
-.IR timezone :
-_SVID_SOURCE || _XOPEN_SOURCE
-.br
-.IR daylight :
-_SVID_SOURCE || _XOPEN_SOURCE
-.SH DESCRIPTION
-The
-.BR tzset ()
-function initializes the \fItzname\fP variable from the
-.B TZ
-environment variable.
-This function is automatically called by the
-other time conversion functions that depend on the timezone.
-In a System-V-like environment, it will also set the variables \fItimezone\fP
-(seconds West of UTC) and \fIdaylight\fP (to 0 if this timezone does not
-have any daylight saving time rules, or to nonzero if there is a time during
-the year when daylight saving time applies).
-.PP
-If the
-.B TZ
-variable does not appear in the environment, the system timezone is used.
-The system timezone is configured by copying, or linking, a file in the
-.BR tzfile "(5) format to"
-.IR /etc/localtime .
-A timezone database of these files may be located in the system
-timezone directory (see the \fBFILES\fP section below).
-.PP
-If the
-.B TZ
-variable does appear in the environment, but its value is empty,
-or its value cannot be interpreted using any of the formats specified
-below, then Coordinated Universal Time (UTC) is used.
-.PP
-The value of
-.B TZ
-can be one of two formats.
-The first format is a string of characters that directly represent the
-timezone to be used:
-.sp
-.RS
-.RI "std offset " dst [ offset ][, start [ /time ], end [ /time ]]
-.RE
-.sp
-There are no spaces in the specification.
-The \fIstd\fP string specifies the name of the timezone and must be
-three or more alphabetic characters.
-The \fIoffset\fP string immediately
-follows \fIstd\fP and specifies the time value to be added to the local
-time to get Coordinated Universal Time (UTC).
-The \fIoffset\fP is positive
-if the local timezone is west of the Prime Meridian and negative if it is
-east.
-The hour must be between 0 and 24, and the minutes and seconds
-0 and 59.
-.PP
-The \fIdst\fP string and \fIoffset\fP specify the name and offset for the
-corresponding daylight saving timezone.
-If the offset is omitted,
-it defaults to one hour ahead of standard time.
-.PP
-The \fIstart\fP field specifies when daylight saving time goes into
-effect and the \fIend\fP field specifies when the change is made back to
-standard time.
-These fields may have the following formats:
-.TP
-J\fIn\fP
-This specifies the Julian day with \fIn\fP between 1 and 365.
-Leap days are not counted.
-In this format, February 29 can't be represented;
-February 28 is day 59, and March 1 is always day 60.
-.TP
-.I n
-This specifies the zero-based Julian day with \fIn\fP between 0 and 365.
-February 29 is counted in leap years.
-.TP
-M\fIm\fP.\fIw\fP.\fId\fP
-This specifies day \fId\fP (0 <= \fId\fP <= 6) of week \fIw\fP
-(1 <= \fIw\fP <= 5) of month \fIm\fP (1 <= \fIm\fP <= 12).
-Week 1 is
-the first week in which day \fId\fP occurs and week 5 is the last week
-in which day \fId\fP occurs.
-Day 0 is a Sunday.
-.PP
-The \fItime\fP fields specify when, in the local time currently in effect,
-the change to the other time occurs.
-If omitted, the default is 02:00:00.
-
-Here is an example for New Zealand,
-where the standard time (NZST) is 12 hours ahead of UTC,
-and daylight saving time (NZDT), 13 hours ahead of UTC,
-runs from the first Sunday in October to the third Sunday in March,
-and the changeovers happen at the default time of 02:00:00:
-.nf
-
- TZ="NZST-12:00:00NZDT-13:00:00,M10.1.0,M3.3.0"
-.fi
-.PP
-The second format specifies that the timezone information should be read
-from a file:
-.sp
-.RS
-:[filespec]
-.RE
-.sp
-If the file specification \fIfilespec\fP is omitted, or its value cannot
-be interpreted, then Coordinated Universal Time (UTC) is used.
-If \fIfilespec\fP is given, it specifies another
-.BR tzfile (5)-format
-file to read the timezone information from.
-If \fIfilespec\fP does not begin with a \(aq/\(aq, the file specification is
-relative to the system timezone directory. If the colon is omitted each
-of the above \fBTZ\fP formats will be tried.
-.PP
-Here's an example, once more for New Zealand:
-.nf
-
- TZ=":Pacific/Auckland"
-.fi
-.SH ENVIRONMENT
-.TP
-.B TZ
-If this variable is set its value takes precedence over the system
-configured timezone.
-.TP
-.B TZDIR
-If this variable is set its value takes precedence over the system
-configured timezone database directory path.
-.SH FILES
-.TP
-.B /etc/localtime
-The system timezone file.
-.TP
-.B /usr/share/zoneinfo/
-The system timezone database directory.
-.TP
-.B /usr/share/zoneinfo/posixrules
-When a TZ string includes a dst timezone without anything following it,
-then this file is used for the start/end rules.
-It is in the
-.BR tzfile "(5) format."
-By default, the zoneinfo Makefile hard links it to the
-.IR America/New_York " tzfile."
-.PP
-Above are the current standard file locations, but they are
-configurable when glibc is compiled.
-.SH CONFORMING TO
-SVr4, POSIX.1-2001, 4.3BSD.
-.SH NOTES
-Note that the variable \fIdaylight\fP does not indicate that daylight
-saving time applies right now.
-It used to give the number of some
-algorithm (see the variable \fItz_dsttime\fP in
-.BR gettimeofday (2)).
-It has been obsolete for many years but is required by SUSv2.
-.LP
-4.3BSD had a function
-.BI "char *timezone(" zone ", " dst )
-that returned the
-name of the timezone corresponding to its first argument (minutes
-West of UTC).
-If the second argument was 0, the standard name was used,
-otherwise the daylight saving time version.
-.SH SEE ALSO
-.BR date (1),
-.BR gettimeofday (2),
-.BR time (2),
-.BR ctime (3),
-.BR getenv (3),
-.BR tzfile (5)
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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