Time zone in date?

Question

From where does the date command in Linux get the time zone information?

I cannot see the /etc/localtime file and the /usr/share/zoneinfo directory on my system. Still, when I execute the date command, I get the following output:

Thu Dec 9 16:28:18 UTC 2010

Kindly tell me: From where does the command get the time zone information?

`/etc/TZ` file is there. But i think the system does not take the time from that file. Because if i modify this file to some other timezone and then reboot, It should show the new timezone. But that does not happen. In my case /etc/TZ is a symbolic link to /etc/cmm/TZ. /etc/cmm/TZ is the file created by my application as part of the root file system. — nitin_cherian, Dec 09 '10 at 09:48

score 3 · Answer 1 · answered Dec 09 '10 at 10:42

Don't forget that UTC is how standard Unix systems store the date/time in the real time clock. You have to jump through hoops using funny programs (see the hwclock(8) manpage) if you dual-boot to Windows, which prefers the local time to be stored in the CMOS real time clock.

So the date(1) program is simply showing you the results of "I have no configured time zone":

# date -u
Thu Dec  9 10:40:54 UTC 2010
# TZ=UTC date
Thu Dec  9 10:40:57 UTC 2010
# TZ=PST8PDT date
Thu Dec  9 02:41:02 PST 2010
#

Thomas · Answer 2 · 2012-10-14T06:56:52.500

From http://www.wikihow.com/Change-the-Timezone-in-Linux

On mobile phones and other small devices that run Linux, the time zone is stored differently. It is written in /etc/TZ, in the format that is described, for instance, in [4] . Edit this file manually or use echo (for instance, echo GMT0BST > /etc/TZ to set the the timezone of the United Kingdom).

From http://www.radisys.com/files/support_downloads/03245-02_MPCMM0001_MPCMM0002_CMM_Software_TPS.pdf

The CMM determines the offset to local timezone maintained in file /etc/cmm/TZ and automatically updates the time.

Time zone in date?

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