1README for the tz distribution 2 3This file is in the public domain, so clarified as of 42009-05-17 by Arthur David Olson. 5 6"What time is it?" -- Richard Deacon as The King 7"Any time you want it to be." -- Frank Baxter as The Scientist 8 (from the Bell System film "About Time") 9 10The 1989 update of the time zone package featured 11 12* POSIXization (including interpretation of POSIX-style TZ environment 13 variables, provided by Guy Harris), 14* ANSIfication (including versions of "mktime" and "difftime"), 15* SVIDulation (an "altzone" variable) 16* MACHination (the "gtime" function) 17* corrections to some time zone data (including corrections to the rules 18 for Great Britain and New Zealand) 19* reference data from the United States Naval Observatory for folks who 20 want to do additional time zones 21* and the 1989 data for Saudi Arabia. 22 23(Since this code will be treated as "part of the implementation" in some places 24and as "part of the application" in others, there's no good way to name 25functions, such as timegm, that are not part of the proposed ANSI C standard; 26such functions have kept their old, underscore-free names in this update.) 27 28And the "dysize" function has disappeared; it was present to allow compilation 29of the "date" command on old BSD systems, and a version of "date" is now 30provided in the package. The "date" command is not created when you "make all" 31since it may lack options provided by the version distributed with your 32operating system, or may not interact with the system in the same way the 33native version does. 34 35Since POSIX frowns on correct leap second handling, the default behavior of 36the "zic" command (in the absence of a "-L" option) has been changed to omit 37leap second information from its output files. 38 39Here is a recipe for acquiring, building, installing, and testing the 40tz distribution on a GNU/Linux or similar host. 41 42 mkdir tz 43 cd tz 44 wget --retr-symlinks 'ftp://ftp.iana.org/tz/tz*-latest.tar.gz' 45 gzip -dc tzcode-latest.tar.gz | tar -xf - 46 gzip -dc tzdata-latest.tar.gz | tar -xf - 47 48Be sure to read the comments in "Makefile" and make any changes needed 49to make things right for your system, especially if you are using some 50platform other than GNU/Linux. Then run the following commands, 51substituting your desired installation directory for "$HOME/tzdir": 52 53 make TOPDIR=$HOME/tzdir install 54 $HOME/tzdir/etc/zdump -v America/Los_Angeles 55 56To use the new functions, use a "-ltz" option when compiling or linking. 57 58Historical local time information has been included here to: 59 60* provide a compendium of data about the history of civil time 61 that is useful even if the data are not 100% accurate; 62 63* give an idea of the variety of local time rules that have 64 existed in the past and thus an idea of the variety that may be 65 expected in the future; 66 67* provide a test of the generality of the local time rule description 68 system. 69 70The information in the time zone data files is by no means authoritative; 71the files currently do not even attempt to cover all time stamps before 721970, and there are undoubtedly errors even for time stamps since 1970. 73If you know that the rules are different from those in a file, by all means 74feel free to change file (and please send the changed version to 75tz@iana.org for use in the future). Europeans take note! 76 77Thanks to these Timezone Caballeros who've made major contributions to the 78time conversion package: Keith Bostic; Bob Devine; Paul Eggert; Robert Elz; 79Guy Harris; Mark Horton; John Mackin; and Bradley White. Thanks also to 80Michael Bloom, Art Neilson, Stephen Prince, John Sovereign, and Frank Wales 81for testing work, and to Gwillim Law for checking local mean time data. 82None of them are responsible for remaining errors. 83 84Look in <ftp://ftp.iana.org/tz/releases/> 85for updated versions of these files. 86 87Please send comments or information to tz@iana.org. 88 89Postscript: The README above is largely unmodified (aside from details 90of mailing list and ftp archive addresses) from that prepared many years 91ago by Arthur David Olson, to whom the timezone community owes the 92greatest debt of all. Arthur is not currently maintaining this data or 93code (though he remains involved). 94