A chkconfig --list would show you the list of services and their run level configurations.
Sample output on a CentOS installation:
# chkconfig --listNetworkManager 0:off 1:off 2:off 3:off 4:off 5:off 6:offacpid 0:off 1:off 2:on 3:on 4:on 5:on 6:offanacron 0:off 1:off 2:on 3:on 4:on 5:on 6:offatd 0:off 1:off 2:off 3:on 4:on 5:on 6:offauditd 0:off 1:off 2:on 3:on 4:on 5:on 6:offautofs 0:off 1:off 2:off 3:on 4:on 5:on 6:offavahi-daemon 0:off 1:off 2:off 3:on 4:on 5:on 6:offavahi-dnsconfd 0:off 1:off 2:off 3:off 4:off 5:off 6:offbluetooth 0:off 1:off 2:on 3:on 4:on 5:on 6:offcapi 0:off 1:off 2:off 3:off 4:off 5:off 6:offconman 0:off 1:off 2:off 3:off 4:off 5:off 6:offcpuspeed 0:off 1:on 2:on 3:on 4:on 5:on 6:offcrond 0:off 1:off 2:on 3:on 4:on 5:on 6:offcups 0:off 1:off 2:on 3:on 4:on 5:on 6:offdnsmasq 0:off 1:off 2:off 3:off 4:off 5:off 6:offdund 0:off 1:off 2:off 3:off 4:off 5:off 6:offfirstboot 0:off 1:off 2:off 3:on 4:off 5:on 6:offgpm 0:off 1:off 2:on 3:on 4:on 5:on 6:offhaldaemon 0:off 1:off 2:off 3:on 4:on 5:on 6:offhidd 0:off 1:off 2:on 3:on 4:on 5:on 6:offip6tables 0:off 1:off 2:on 3:on 4:on 5:on 6:offiptables 0:off 1:off 2:on 3:on 4:on 5:on 6:offirda 0:off 1:off 2:off 3:off 4:off 5:off 6:offirqbalance 0:off 1:off 2:on 3:on 4:on 5:on 6:offisdn 0:off 1:off 2:on 3:on 4:on 5:on 6:offkudzu 0:off 1:off 2:off 3:on 4:on 5:on 6:offlvm2-monitor 0:off 1:on 2:on 3:on 4:on 5:on 6:offmcstrans 0:off 1:off 2:on 3:on 4:on 5:on 6:offmdmonitor 0:off 1:off 2:on 3:on 4:on 5:on 6:offmdmpd 0:off 1:off 2:off 3:off 4:off 5:off 6:offmessagebus 0:off 1:off 2:off 3:on 4:on 5:on 6:offmicrocode_ctl 0:off 1:off 2:on 3:on 4:on 5:on 6:offmultipathd 0:off 1:off 2:off 3:off 4:off 5:off 6:offmysqld 0:off 1:off 2:off 3:off 4:off 5:off 6:offnetconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:offnetfs 0:off 1:off 2:off 3:on 4:on 5:on 6:offnetplugd 0:off 1:off 2:off 3:off 4:off 5:off 6:offnetwork 0:off 1:off 2:on 3:on 4:on 5:on 6:offnfs 0:off 1:off 2:off 3:off 4:off 5:off 6:offnfslock 0:off 1:off 2:off 3:on 4:on 5:on 6:offnscd 0:off 1:off 2:off 3:off 4:off 5:off 6:offntpd 0:off 1:off 2:on 3:on 4:on 5:on 6:offoddjobd 0:off 1:off 2:off 3:off 4:off 5:off 6:offpand 0:off 1:off 2:off 3:off 4:off 5:off 6:offpcscd 0:off 1:off 2:on 3:on 4:on 5:on 6:offportmap 0:off 1:off 2:off 3:on 4:on 5:on 6:offpsacct 0:off 1:off 2:off 3:off 4:off 5:off 6:offrawdevices 0:off 1:off 2:off 3:on 4:on 5:on 6:offrdisc 0:off 1:off 2:off 3:off 4:off 5:off 6:offreadahead_early 0:off 1:off 2:on 3:on 4:on 5:on 6:offreadahead_later 0:off 1:off 2:off 3:off 4:off 5:on 6:offrestorecond 0:off 1:off 2:on 3:on 4:on 5:on 6:offrpcgssd 0:off 1:off 2:off 3:on 4:on 5:on 6:offrpcidmapd 0:off 1:off 2:off 3:on 4:on 5:on 6:offrpcsvcgssd 0:off 1:off 2:off 3:off 4:off 5:off 6:offsaslauthd 0:off 1:off 2:off 3:off 4:off 5:off 6:offsendmail 0:off 1:off 2:on 3:on 4:on 5:on 6:offsmartd 0:off 1:off 2:on 3:on 4:on 5:on 6:offsshd 0:off 1:off 2:on 3:on 4:on 5:on 6:offsyslog 0:off 1:off 2:on 3:on 4:on 5:on 6:offtcsd 0:off 1:off 2:off 3:off 4:off 5:off 6:offwpa_supplicant 0:off 1:off 2:off 3:off 4:off 5:off 6:offxfs 0:off 1:off 2:on 3:on 4:on 5:on 6:offypbind 0:off 1:off 2:off 3:off 4:off 5:off 6:offyum-updatesd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
To add a new service to this list, an example in this case - httpd,
# chkconfig --add httpd
The list would now include httpd,
# chkconfig --list | grep httpdAs seen above, it will not run automatically on any run level. I wanted it to run on 2,3,4 and 5 and hence,
httpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
And to check the new configuration,# chkconfig --level 2345 httpd on
A reboot can actually verify whether this configuration works.# chkconfig --list | grep httpdhttpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
chkconfig is not available on Ubuntu by default, but can be installed like so,
# sudo apt-get install chkconfig