Sources for Time Zone and Daylight Saving Time Data

@(#)tz-link.htm 7.32

Please send corrections to this web page to the time zone mailing list.

The tz database

The public-domain time zone database contains code and data that represent the history of local time for many representative locations around the globe. It is updated periodically to reflect changes made by political bodies to UTC offsets and daylight-saving rules. This database (often called tz or zoneinfo) is used by several implementations, including GNU/Linux, FreeBSD, NetBSD, OpenBSD, DJGPP, HP-UX, IRIX, SCO OpenServer, Solaris, Tru64, and UnixWare.

In the tz database's FTP distribution, the code is in the file tzcodeC.tar.gz, where C is the code's version; similarly, the data are in tzdataD.tar.gz, where D is the data's version. The following shell commands use GNU wget to download these files to a GNU/Linux or similar host; see the downloaded README file for what to do next.

mkdir tz
cd tz
wget 'ftp://elsie.nci.nih.gov/pub/tz*.tar.gz'
gzip -dc tzcode*.tar.gz | tar -xf -
gzip -dc tzdata*.tar.gz | tar -xf -

The code lets you compile the tz source files into machine-readable binary files, one for each location. It also lets you read a tz binary file and interpret time stamps for that location.

The data are by no means authoritative. If you find errors, please send changes to the time zone mailing list. You can also subscribe to the mailing list, or retrieve the archive of old messages (in gzip compressed format).

The Web has several other sources for time zone and daylight saving time data. Here are some recent links that may be of interest.

Web pages using recent versions of the tz database

Other tz compilers

Other tz binary file readers

Other tz-based time zone conversion software

Other time zone databases

Maps

Time zone boundaries

Daylight saving time concepts and history

Precision timekeeping

Time notation

Related indexes