#select jenkins.war location
ps aux | grep jenkins
cd /var/lib/jenkins/downloads
cd /downloads
wget http://updates.jenkins-ci.org/download/war/[jenkins version]/jenkins.war
#backup current jenkins war
cp /usr/share/jenkins/jenkins.war jenkins.war.previous.version
#copy new version to startup location
cp jenkins.war /usr/share/jenkins/
sudo service jenkins stop
sudo service jenkins start