Centos – Why is $ date still displaying EST when /etc/localtime is symlinked to /usr/share/zoneinfo/GMT

centosdatetimezone

I'm having a problem setting the date on my server…

$ ls -la /etc | grep localtime
lrwxrwxrwx  1 root root  23 Mar 6  12:07 /etc/localtime -> /usr/share/zoneinfo/GMT

For some reason, although the time 17:31:06 is GMT, the timezone suffix is EST…

$ date
Tue Mar  6 17:31:06 EST 2012

And the hardware clock is also messed up – 10:32:12 isn't EST:

$ hwclock --show
Tue 06 Mar 2012 10:32:12 PM EST  -0.000276 seconds

If I set the hwclock to the system time or localtime, it sets it incorrectly:

$ hwclock --localtime
Tue 06 Mar 2012 10:34:22 PM EST  -0.000190 seconds
$ date
Tue Mar  6 17:34:24 EST 2012

Any idea what is going on?

Thanks

Best Answer

Three Simple Rules for Not Going Insane When Dealing With Time:

First: You're running Unix (and presumably NTP): Make sure you have set your system's BIOS/Hardware clock to UTC.
The absolute last thing you need is your hardware (BIOS) clock fighting with Unix over whose timezone is right and when daylight saving time begins/ends. Setting your hardware clock to UTC makes life much easier.

Second: When you change the system-wide time zone you sometimes need to log out and log back in again for the system to understand what happened. Generally I suggest rebooting - this ensures every part of the OS has been kicked in the head and understands what has happened.
You don't want cron still running in US/Eastern time when you've changed the machine's timezone to Hawaii.

Third: If you user account still has a messed-up idea of the time zone something is probably setting the TZ environment variable -- double-check your .profile and shell rc files.
Unix doesn't assume that every user on the system is in the local time zone, so it lets you override on a per-user (or per-shell) level. This is very useful if your system is running on (e.g.) US/Eastern time and you have users logging in from Japan - People like the time their system reports to match the clock on their wall :)

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