$ curl cheat.sh/
# chkconfig
# Manage the runlevel of services on CentOS 6.
# More information: <https://manned.org/chkconfig>.

# List services with runlevel:
chkconfig --list

# Show a service's runlevel:
chkconfig --list ntpd

# Enable service at boot:
chkconfig sshd on

# Enable service at boot for runlevels 2, 3, 4, and 5:
chkconfig --level 2345 sshd on

# Disable service at boot:
chkconfig ntpd off

# Disable service at boot for runlevel 3:
chkconfig --level 3 ntpd off

$
Follow @igor_chubin cheat.sh tldr