Timezone setting in Linux

I’m setting the timezone to GMT+6 on my Linux machine by copying the zoneinfo file to /etc/localtime, but the date command is still showing the time as UTCtime-6. Can any one explain to me this behavior?

I’m assuming the date command should display UTCtime+6 time. Here are steps I’m following:

Wed Jan 22 17:29:01 IST 2014

date -u
Wed Jan 22 11:59:01 UTC 2014

cp /usr/share/zoneinfo/Etc/GMT+6 /etc/localtime

Wed Jan 22 05:59:21 GMT+6 2014

date -u
Wed Jan 22 11:59:01 UTC 2014
Asked By: Rahul Dhobi


Take a look at this blog post titled: How To: 2 Methods To Change TimeZone in Linux.

Red Hat distros

If you’re using a distribution such as Red Hat then your approach of copying the file would be mostly acceptable.

NOTE: If you’re looking for a distro-agnostic solution, this also works on Debian, though there are simpler approaches below if you only need to be concerned with Debian machines.

$ ls /usr/share/zoneinfo/
Africa/      CET          Etc/         Hongkong     Kwajalein    Pacific/     ROK          zone.tab
America/     Chile/       Europe/      HST          Libya        Poland       Singapore    Zulu
Antarctica/  CST6CDT      GB           Iceland      MET          Portugal     Turkey       
Arctic/      Cuba         GB-Eire      Indian/      Mexico/      posix/       UCT          
Asia/        EET          GMT          Iran         MST          posixrules   Universal    
Atlantic/    Egypt        GMT0         iso3166.tab  MST7MDT      PRC          US/          
Australia/   Eire         GMT-0        Israel       Navajo       PST8PDT      UTC          
Brazil/      EST          GMT+0        Jamaica      NZ           right/       WET          
Canada/      EST5EDT      Greenwich    Japan        NZ-CHAT      ROC          W-SU         

I would recommend linking to it rather than copying however.

$ sudo unlink /etc/localtime 
$ sudo ln -s /usr/share/zoneinfo/Etc/GMT+6 /etc/localtime

Now date shows the different timezone:

$ date -u
Thu Jan 23 05:40:31 UTC 2014

$ date 
Wed Jan 22 23:40:38 GMT+6 2014

Ubuntu/Debian Distros

To change the timezone on either of these distros you can use this command:

$ sudo dpkg-reconfigure tzdata

    ss #1

$ sudo dpkg-reconfigure tzdata

Current default time zone: 'Etc/GMT-6'
Local time is now:      Thu Jan 23 11:52:16 GMT-6 2014.
Universal Time is now:  Thu Jan 23 05:52:16 UTC 2014.

Now when we check it out:

$ date -u
Thu Jan 23 05:53:32 UTC 2014

$ date 
Thu Jan 23 11:53:33 GMT-6 2014

NOTE: There’s also this option in Ubuntu 14.04 and higher with a single command (source: Ask Ubuntu – setting timezone from terminal):

$ sudo timedatectl set-timezone Etc/GMT-6

On the use of “Etc/GMT+6”

excerpt from @MattJohnson’s answer on SO

Zones like Etc/GMT+6 are intentionally reversed for backwards compatibility with POSIX standards. See the comments in this file.

You should almost never need to use these zones. Instead you should be using a fully named time zone like America/New_York or Europe/London or whatever is appropriate for your location. Refer to the list here.

Answered By: slm

tzselect command is made to do what you want.

Answered By: SHW

This is how I do it in Ubuntu. Just replace Asia/Tokyo with your own timezone.

echo 'Asia/Tokyo' | sudo tee /etc/timezone

sudo dpkg-reconfigure -f noninteractive tzdata

There is a bug in tzdata: certain values get normalized by dpkg-reconfigure:

echo 'US/Central' >/etc/timezone
dpkg-reconfigure -f noninteractive tzdata
# Current default time zone: 'America/Chicago'

echo 'US/Eastern' >/etc/timezone
apt-get install --reinstall tzdata
# Current default time zone: 'America/New_York'
Answered By: user241
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