How to restart Jenkins manually?

To restart Jenkins manually, you can use either of the following commands (by entering their URL in a browser):

(jenkins_url)/safeRestart - Allows all running jobs to complete. New jobs will remain in the queue to run after the restart is complete.

(jenkins_url)/restart - Forces a restart without waiting for builds to complete.

The SafeRestart Plugin needs to be mentioned. It is pretty useful (Restart Safely). It adds a link to be able to restart from the main menu:

If you installed as a rpm or deb, then service jenkins restart will work also.

On Ubuntu or Debian, when installed through apt-get/dpkg:

$ sudo /etc/init.d/jenkins restart
Usage: /etc/init.d/jenkins {start|stop|status|restart|force-reload}