I just noticed my Jenkins last wrote jenkins.log in /var/log/jenkins for more than 6 months ago.
This is from my Jenkins config:
# log location. this may be a syslog facility.priority JENKINS_LOG=/var/log/$NAME/$NAME.log #JENKINS_LOG=daemon.info
So why no new logs being written there? Files and directory permission for this log location is the same as freshly new installed Jenkins.