Manage services with update-rc.d in Ubuntu

If the particular services not started at during the boot time, usually we start the service in ubuntu under /etc/init.d/

# /etc/init.d/ssh start

In Ubuntu, command “update-rc.d” is the simple way used to configure services start at certain levels and priority
Adding services with Default Priority

root@ubuntu:~# update-rc.d -f ssh defaults
Adding system startup for /etc/init.d/ssh …
/etc/rc0.d/K20ssh -> ../init.d/ssh
/etc/rc1.d/K20ssh -> ../init.d/ssh
/etc/rc6.d/K20ssh -> ../init.d/ssh
/etc/rc2.d/S20ssh -> ../init.d/ssh
/etc/rc3.d/S20ssh -> ../init.d/ssh
/etc/rc4.d/S20ssh -> ../init.d/ssh
/etc/rc5.d/S20ssh -> ../init.d/ssh
root@ubuntu:~#

Adding services with Custom Priority

root@ubuntu:~# update-rc.d -f ssh defaults 91
Adding system startup for /etc/init.d/ssh …
/etc/rc0.d/K91ssh -> ../init.d/ssh
/etc/rc1.d/K91ssh -> ../init.d/ssh
/etc/rc6.d/K91ssh -> ../init.d/ssh
/etc/rc2.d/S91ssh -> ../init.d/ssh
/etc/rc3.d/S91ssh -> ../init.d/ssh
/etc/rc4.d/S91ssh -> ../init.d/ssh
/etc/rc5.d/S91ssh -> ../init.d/ssh
root@ubuntu:~#

Adding services with different Priorities for Start and Kill

root@ubuntu:~# update-rc.d -f ssh defaults 20 90
Adding system startup for /etc/init.d/ssh …
/etc/rc0.d/K90ssh -> ../init.d/ssh
/etc/rc1.d/K90ssh -> ../init.d/ssh
/etc/rc6.d/K90ssh -> ../init.d/ssh
/etc/rc2.d/S20ssh -> ../init.d/ssh
/etc/rc3.d/S20ssh -> ../init.d/ssh
/etc/rc4.d/S20ssh -> ../init.d/ssh
/etc/rc5.d/S20ssh -> ../init.d/ssh
root@ubuntu:~#

Specific with Custom Runlevels

root@ubuntu:~# update-rc.d -f ssh start 20 2 3 4 5 . stop 90 0 1 6 .
Adding system startup for /etc/init.d/ssh …
/etc/rc0.d/K90ssh -> ../init.d/ssh
/etc/rc1.d/K90ssh -> ../init.d/ssh
/etc/rc6.d/K90ssh -> ../init.d/ssh
/etc/rc2.d/S20ssh -> ../init.d/ssh
/etc/rc3.d/S20ssh -> ../init.d/ssh
/etc/rc4.d/S20ssh -> ../init.d/ssh
/etc/rc5.d/S20ssh -> ../init.d/ssh
root@ubuntu:~#