Sync zoneinfo database with tzdata2009h from elsie.
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1@(#)README 8.3
2This file is in the public domain, so clarified as of
32009-05-17 by Arthur David Olson.
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4
5"What time is it?" -- Richard Deacon as The King
6"Any time you want it to be." -- Frank Baxter as The Scientist
7 (from the Bell System film "About Time")
8
9The 1989 update of the time zone package featured
10
11* POSIXization (including interpretation of POSIX-style TZ environment
12 variables, provided by Guy Harris),
13* ANSIfication (including versions of "mktime" and "difftime"),
14* SVIDulation (an "altzone" variable)
15* MACHination (the "gtime" function)
16* corrections to some time zone data (including corrections to the rules
17 for Great Britain and New Zealand)
18* reference data from the United States Naval Observatory for folks who
19 want to do additional time zones
20* and the 1989 data for Saudi Arabia.
21
22(Since this code will be treated as "part of the implementation" in some places
23and as "part of the application" in others, there's no good way to name
24functions, such as timegm, that are not part of the proposed ANSI C standard;
25such functions have kept their old, underscore-free names in this update.)
26
27And the "dysize" function has disappeared; it was present to allow compilation
28of the "date" command on old BSD systems, and a version of "date" is now
29provided in the package. The "date" command is not created when you "make all"
30since it may lack options provided by the version distributed with your
31operating system, or may not interact with the system in the same way the
32native version does.
33
34Since POSIX frowns on correct leap second handling, the default behavior of
35the "zic" command (in the absence of a "-L" option) has been changed to omit
36leap second information from its output files.
37
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38Here is a recipe for acquiring, building, installing, and testing the
39tz distribution on a GNU/Linux or similar host.
40
41 mkdir tz
42 cd tz
43 wget 'ftp://elsie.nci.nih.gov/pub/tz*.tar.gz'
44 gzip -dc tzcode*.tar.gz | tar -xf -
45 gzip -dc tzdata*.tar.gz | tar -xf -
46
47Be sure to read the comments in "Makefile" and make any changes needed
48to make things right for your system, especially if you are using some
49platform other than GNU/Linux. Then run the following commands,
50substituting your desired installation directory for "$HOME/tzdir":
51
52 make TOPDIR=$HOME/tzdir install
53 $HOME/tzdir/etc/zdump -v America/Los_Angeles
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54
55To use the new functions, use a "-ltz" option when compiling or linking.
56
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57Historical local time information has been included here to:
58
59* provide a compendium of data about the history of civil time
60 that is useful even if the data are not 100% accurate;
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61
62* give an idea of the variety of local time rules that have
63 existed in the past and thus an idea of the variety that may be
64 expected in the future;
65
66* provide a test of the generality of the local time rule description
67 system.
68
69The information in the time zone data files is by no means authoritative;
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70the files currently do not even attempt to cover all time stamps before
711970, and there are undoubtedly errors even for time stamps since 1970.
72If you know that the rules are different from those in a file, by all means
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73feel free to change file (and please send the changed version to
74tz@elsie.nci.nih.gov for use in the future). Europeans take note!
75
76Thanks to these Timezone Caballeros who've made major contributions to the
77time conversion package: Keith Bostic; Bob Devine; Paul Eggert; Robert Elz;
78Guy Harris; Mark Horton; John Mackin; and Bradley White. Thanks also to
79Michael Bloom, Art Neilson, Stephen Prince, John Sovereign, and Frank Wales
80for testing work, and to Gwillim Law for checking local mean time data.
81None of them are responsible for remaining errors.
82
83Look in the ~ftp/pub directory of elsie.nci.nih.gov
84for updated versions of these files.
85
86Please send comments or information to tz@elsie.nci.nih.gov.