Jenkins failed to start in linux

So, knowing it was a pre-start error allowed me to investigate more deeply.

Further digging allowed me to figure out that the exact line in the /etc/init/jenkins.conf file was one pointing to the /usr/share/jenkins/bin/maintain-plugins.sh

Looking at this location, I found it was not present (ie. no bin directory). This means that jenkins-common was no longer installed for some reason...odd indeed...going into apt-get and doing an install of this component again led to the error:

dpkg error processing /var/cache/apt/archives/jenkins-common_1.409.1-0ubuntu4.2_all.deb ...

having seen this error before and refreshing my memory via google gave the following solution:

dpkg -i --force-overwrite /var/cache/apt/archives/jenkins-common_1.409.1-0ubuntu4.2_all.deb

This allowed the installation of common to proceed as normal. After this, all I had to do was replace the /usr/share/jenkins/jenkins.war with my backed up copy (because ubuntu is far behind the latest release version), and I was able to start the server again.

I am not exactly sure what caused the problem to begin with, but it was likely during an apt-get upgrade/clean process...and because of the weirdness with jenkins conflicting with jenkins-common, it did not repopulate the /usr/share/jenkins directory properly.

regardless, am glad it is working again. :)

Instead, you can run the following before the install to properly clean up any conffiles left by the distro version:

sudo apt-get purge jenkins

Then install the correct version.

I went to see the jenkins logstail -f /var/log/jenkins/jenkins.log

In my case it didn't start because I used incompatible java version.Update and make sure it sees correct java (In my case it should have been opened using JRE 1.7. To check, please use java -version command) and all should work