Chkconfig command

# chkconfig --list
With this command, you will see a list of system services and whether they are started (on) or stopped (off) in runlevels 0-6

To check a particular service .. in my example sendmail

root@inf1sysadm1 ~]# chkconfig --list sendmail
sendmail 0:off 1:off 2:on 3:on 4:off 5:on 6:off

#chkconfig 235 on

If you found any serivce run in run level 4,6 as well... use following command to stop.
In my example only run in 4th run level.

[root@inf1sysadm1 ~]# chkconfig --list | grep sendmail
sendmail 0:off 1:off 2:on 3:on 4:on 5:on 6:off

[root@inf1sysadm1 ~]# chkconfig --level 4 sendmail off

[root@inf1sysadm1 ~]# chkconfig --list | grep sendmail
sendmail 0:off 1:off 2:on 3:on 4:off 5:on 6:off