A typical unix service-related command looks like this

# start mysql service
service mysqld start

# stop mysql service
service mysqld stop

The list of currently configures service can be viewed using chkconfig command

[root ~]# chkconfig --list
...
ip6tables       0:off   1:off   2:on    3:on    4:on    5:on    6:off
iptables        0:off   1:off   2:on    3:on    4:on    5:on    6:off
messagebus      0:off   1:off   2:on    3:on    4:on    5:on    6:off
mysqld          0:off   1:off   2:off   3:off   4:off   5:off   6:off
netconsole      0:off   1:off   2:off   3:off   4:off   5:off   6:off
netfs           0:off   1:off   2:off   3:on    4:on    5:on    6:off
...

Each of the number 0-6 corresponds to different OS runlevel.

To disable/enable mysqld service, use following command

# disable mysqld
chkconfig mysqld off

# enable mysqld
chkconfig mysqld on

By default chkconfig on/off will set the service into 2-5 runlevel.