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Configuring the Date and Time on a RedHat Linux System.

Sun, 2007-04-01 14:24 — tima

Have you ever wondered how to easily change the date, time, and time zone configuration on your RedHat Linux server? Every once in a while I need to manipulate the date or time, especially when I ship servers to a new location in a different time zone, and I always fumble around for the commands.

Here is the easiest and fastest method I can find to do this:

  1. First of all you need an X-Server running. Either start one up remotely on your workstation, or login to the graphical login screen on the console to your server.
  2. Now run the appropriate RedHat utility to set your time as the root user.

    On RedHat AS4, the command is:

    /usr/bin/system-config-time

    On RedHat AS3, the command is:

    /usr/bin/redhat-config-time
  3. This will open a GUI display from which you can quicky change the date, time, and time zone for your server. This utility is pretty self explanatory on how to use.

  4. Another setting I'll change through this utility is to point my server at a Network Time Protocol (NTP) server. This helps to ensure that it's date and time are kept as accurate as possible by synchronizing it's time with a group of external time servers. To do this, use the configuration utility above and go to the "Network Time Protocol" tab.

    In the text box labeled Server add a few NTP servers. I'll usually add the following 3 servers:

    0.pool.ntp.org
1.pool.ntp.org
2.pool.ntp.org

    Simply add the servers listed above, one at a time, into the Server text box and then click on the Add button.

  5. Click the OK button to close down the Date/Time utility. Your time should now be properly configured.
  6. At your shell prompt you can run the ntpq command to check the synchronization status of your server with the external time serves.

    As root, run the command:

    ntpq -p

    And your output should look something like:

    root@as1 filmoregroup.com [asdb] > ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
+ns1.dns.pciwest 204.123.2.5      2 u  562 1024  377   76.131   -2.912   1.129
+dns1.tjgroup.no 192.43.244.18    2 u  550 1024  377  143.463    1.390   0.422
*time4.stupi.se  .PPS.            1 u  604 1024  377  122.685    0.087   0.492
 LOCAL(0)        LOCAL(0)        10 l   35   64  377    0.000    0.000   0.001

    If the jitter column has a value of 4000.00 for any of the servers then it is usually a sign that your server is not able to synchronize with that server specified on the line with the bad jitter value. You may have a firewall or other internet connectivity problem then.



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