Make sure Jenkins is always running. This script is meant to be run on a cron job under the root user.

enforce-jenkins-running.sh

#!/bin/bash
#
# Makes sure Jenkins is running.

# Function to restart Jenkins, record the occurrence, and exit.
restart_jenkins() {
    /usr/sbin/service jenkins restart > /dev/null
    echo `date` "Restarted Jenkins" >> ~/jenkins-restarts
    echo "Restarted Jenkins."
    exit
}

# If Jenkins is not running, restart it.
if ps aux | grep -v grep | grep "[j]enkins" > /dev/null
then
    # Do nothing. Nothing at all.
    echo "Jenkins is running." > /dev/null
else
    restart_jenkins
fi