I kill jenkins process and started again. After the restart, all the jobs are disappeard. However in my jenkins directory under "jobs" I can see all the job folder still exist.
/app/jenkins
Look like somehow I need to tell the jenkins to pickup all the configuration from existing directory. But not sure how to do.
Any help would be appreciated.
It was a mistake on my part. The reason Jenkins didn't pick up the old jobs is that upon restart, I did not have my JENKINS_HOME environment variable defined. Thus Jenkins didn't pick up the old jobs.
export JENKINS_HOME=/app/jenkins