xref: /freebsd/contrib/tzcode/README (revision 46c599340f187db577b9212ab18022f3c7380c68)
1bc421551SDag-Erling SmørgravREADME for the tz distribution
2bc421551SDag-Erling Smørgrav
3bc421551SDag-Erling Smørgrav"Where do I set the hands of the clock?" -- Les Tremayne as The King
4bc421551SDag-Erling Smørgrav"Oh that--you can set them any place you want." -- Frank Baxter as The Scientist
5bc421551SDag-Erling Smørgrav					(from the Bell System film "About Time")
6bc421551SDag-Erling Smørgrav
7bc421551SDag-Erling SmørgravThe Time Zone Database (called tz, tzdb or zoneinfo) contains code and
8bc421551SDag-Erling Smørgravdata that represent the history of local time for many representative
9bc421551SDag-Erling Smørgravlocations around the globe.  It is updated periodically to reflect
10bc421551SDag-Erling Smørgravchanges made by political bodies to time zone boundaries, UTC offsets,
11bc421551SDag-Erling Smørgravand daylight-saving rules.
12bc421551SDag-Erling Smørgrav
13bc421551SDag-Erling SmørgravSee <https://www.iana.org/time-zones/repository/tz-link.html> or the
14*46c59934SDag-Erling Smørgravfile tz-link.html for how to acquire the code and data.
15bc421551SDag-Erling Smørgrav
16*46c59934SDag-Erling SmørgravOnce acquired, read the leading comments in the file "Makefile"
17*46c59934SDag-Erling Smørgravand make any changes needed to make things right for your system,
18*46c59934SDag-Erling Smørgravespecially when using a platform other than current GNU/Linux.
19*46c59934SDag-Erling Smørgrav
20*46c59934SDag-Erling SmørgravThen run the following commands, substituting your desired
21*46c59934SDag-Erling Smørgravinstallation directory for "$HOME/tzdir":
22*46c59934SDag-Erling Smørgrav
23*46c59934SDag-Erling Smørgrav	make TOPDIR="$HOME/tzdir" install
24*46c59934SDag-Erling Smørgrav	"$HOME/tzdir/usr/bin/zdump" -v America/Los_Angeles
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26bc421551SDag-Erling SmørgravSee the file tz-how-to.html for examples of how to read the data files.
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28bc421551SDag-Erling SmørgravThis database of historical local time information has several goals:
29bc421551SDag-Erling Smørgrav
30bc421551SDag-Erling Smørgrav * Provide a compendium of data about the history of civil time that
31bc421551SDag-Erling Smørgrav   is useful even if not 100% accurate.
32bc421551SDag-Erling Smørgrav
33bc421551SDag-Erling Smørgrav * Give an idea of the variety of local time rules that have existed
34bc421551SDag-Erling Smørgrav   in the past and thus may be expected in the future.
35bc421551SDag-Erling Smørgrav
36bc421551SDag-Erling Smørgrav * Test the generality of the local time rule description system.
37bc421551SDag-Erling Smørgrav
38bc421551SDag-Erling SmørgravThe information in the time zone data files is by no means authoritative;
39bc421551SDag-Erling Smørgravfixes and enhancements are welcome.  Please see the file CONTRIBUTING
40bc421551SDag-Erling Smørgravfor details.
41bc421551SDag-Erling Smørgrav
42bc421551SDag-Erling SmørgravThanks to these Time Zone Caballeros who've made major contributions to the
43bc421551SDag-Erling Smørgravtime conversion package: Keith Bostic; Bob Devine; Paul Eggert; Robert Elz;
44bc421551SDag-Erling SmørgravGuy Harris; Mark Horton; John Mackin; and Bradley White.  Thanks also to
45bc421551SDag-Erling SmørgravMichael Bloom, Art Neilson, Stephen Prince, John Sovereign, and Frank Wales
46bc421551SDag-Erling Smørgravfor testing work, and to Gwillim Law for checking local mean time data.
47bc421551SDag-Erling SmørgravThanks in particular to Arthur David Olson, the project's founder and first
48bc421551SDag-Erling Smørgravmaintainer, to whom the time zone community owes the greatest debt of all.
49bc421551SDag-Erling SmørgravNone of them are responsible for remaining errors.
50bc421551SDag-Erling Smørgrav
51bc421551SDag-Erling Smørgrav-----
52bc421551SDag-Erling Smørgrav
53bc421551SDag-Erling SmørgravThis file is in the public domain, so clarified as of 2009-05-17 by
54bc421551SDag-Erling SmørgravArthur David Olson.  The other files in this distribution are either
55bc421551SDag-Erling Smørgravpublic domain or BSD licensed; see the file LICENSE for details.
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