If you have upgraded your Ubuntu machine to Ubuntu Saucy 13.10, one of the things that you might find missing is the date/time indicator in the menu bar. And if you visit the “System Settings -> Time and Date -> Clock” section, you might find that the option to add it to the menu bar is greyed out and disabled.
If you are having this problem, here’s the fix.
1. Reinstall indicator-datetime. It should be installed by default, but just in case you have removed it unknowingly, it is best to run the install command again.
sudo apt-get install indicator-datetime
2. Next, we are going to reconfigure the date time:
sudo dpkg-reconfigure --frontend noninteractive tzdata
3. Lastly, restart unity.
sudo killall unity-panel-service
That’s it. The date and time indicator will appear in the menu bar now.