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What command(s) can I use to examine the contents of the timezone files, such as /etc/localtime or the files under /usr/share/zoneinfo/*?

Evgeny Vereshchagin
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slm
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3 Answers3

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The most appropriate command would appear to be zdump.

$ zdump /etc/localtime 
/etc/localtime  Wed Aug  7 23:52:25 2013 EDT

$ zdump /usr/share/zoneinfo/* | tail -10
/usr/share/zoneinfo/Singapore    Thu Aug  8 11:52:48 2013 SGT
/usr/share/zoneinfo/Turkey       Thu Aug  8 06:52:48 2013 EEST
/usr/share/zoneinfo/UCT          Thu Aug  8 03:52:48 2013 UCT
/usr/share/zoneinfo/Universal    Thu Aug  8 03:52:48 2013 UTC
/usr/share/zoneinfo/US           Thu Aug  8 03:52:48 2013
/usr/share/zoneinfo/UTC          Thu Aug  8 03:52:48 2013 UTC
/usr/share/zoneinfo/WET          Thu Aug  8 04:52:48 2013 WEST
/usr/share/zoneinfo/W-SU         Thu Aug  8 07:52:48 2013 MSK
/usr/share/zoneinfo/zone.tab     Thu Aug  8 03:52:48 2013
/usr/share/zoneinfo/Zulu         Thu Aug  8 03:52:48 2013 UTC

You can also interrogate these files using the file command:

$ file /etc/localtime 
/etc/localtime: timezone data, version 2, 4 gmt time flags, 4 std time flags, no leap seconds, 235 transition times, 4 abbreviation chars

$ file /usr/share/zoneinfo/Singapore
/usr/share/zoneinfo/Singapore: timezone data, version 2, 8 gmt time flags, 8 std time flags, no leap seconds, 8 transition times, 8 abbreviation chars
slm
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    To extract maximum detail, - Give `-v` option to `zdump(8)`. - If focusing on a particular city, be sure to prepend the country-or-continent prefix (or just give the TZ file's absolute path). Singapore, which is both a country and a city, is a special case: `zdump -v Singapore` and `zdump -v Asia/Singapore` print same result. But you will get far less information from `zdump -v Berlin` than from `zdump -v Europe/Berlin`, for example. – Vainstein K Dec 19 '20 at 02:00
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### For OpenWrt only ### Fixes /etc/TZ and /etc/localtime

curl -so - https://who.is/whois-ip/ip-address/`curl -s ifconfig.me`|\
    egrep 'Country:|City:'

IAMIN=Europe/Amsterdam
tail -1 /usr/share/zoneinfo/$IAMIN | tee /tmp/TZ
ln -s /usr/share/zoneinfo/$IAMIN /tmp/localtime
cinober
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    Welcome to the site, and thank you for your contribution. Please consider adding some explanation to your post. For example, on most recent Unix/Linux systems the files in `zoneinfo` are binary, so the `tail` command will not yield readable output. Also, please explain what the `ln` command is supposed to do in respect to the OPs question of "how to examine the contents". – AdminBee Feb 24 '21 at 11:05
  • @AdminBee I think the `ln` command is supposed to relink the timezone, but the file was accidentally linked to `/tmp`, not `/etc`. – Amint Feb 27 '21 at 23:45
  • @AdminBee I know zoneinfo files are binary, but it just happens to be that they end in normal text line. As stackexchanger sugested "strings /etc/localtime | tail -1" also works. Non-related... To minimize the intrusion into default OpenWrt setup, linked files are in /tmp as OpenWrt have default links from /etc to /tmp. The goal was to correct the localtime-zone as terminal "uci set ..." setup of timezone did not do the work. Lately I found out that confirming the "uci set ..." setup in web-luci seemingly eliminates the problem, by adding some "default" settings; not sure, just seems like. – cinober May 15 '21 at 06:00
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Try tzdump. I found it here: http://www.cise.ufl.edu/~seeger/dist/tzdump.c It is a C program and so will need to be compiled.

Greg McFarlane
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    That program includes `tzfile.h` which does not appear to be available. There is a [github copy](https://github.com/alexandrebelloni/tzdump) of the same program which also lacks `tzfile.h`. – wallyk Sep 17 '15 at 03:10