Update Jenkins
This update applies only if you need to install a new version of Jenkins, but does not affect to Jenkins plugins. In case you want to update plugins, it can be done from the Jenkins UI, on Manage Jenkins > Manage Plugins.
1. Remove current deployment
1.1 Stop Tomcat service
$ sudo service tomcat8 stop
1.2 Rename current Jenkins war
$ sudo mv /opt/jenkins/tomcat-webapps/ROOT.war /opt/jenkins/tomcat-webapps/jenkins.war.OLD
1.3 Remove the current deployment
$ rm -r /opt/jenkins/tomcat-webapps/ROOT
2. Install latest Jenkins war
2.1 Download the latest stable version of Jenkins via wget command to /opt/tomcat-webapps-jenkins folder
$ sudo wget http://mirrors.jenkins-ci.org/war-stable/latest/jenkins.war -O /opt/jenkins/tomcat-webapps/ROOT.war
2.2 Set proper owner
$ sudo chown -R tomcat8:tomcat8 /opt/jenkins
3. Start the service
3.1 Start the Apache Tomcat service
$ sudo service tomcat8 start
