chkconfig

List services with runlevel

$ chkconfig --list

$ chkconfig --list [ntpd]

$ chkconfig [sshd] on

$ chkconfig --level [2345] [sshd] on

$ chkconfig [ntpd] off

$ chkconfig --level [3] [ntpd] off

chkconfig [options] [name] [on|off|reset]

chkconfig manages service runlevels on Red Hat-based Linux systems using SysVinit. It updates the symbolic links in /etc/rc.d/ directories that control which services start at each runlevel.
This tool is primarily used on CentOS 6 and older RHEL systems. Modern systems using systemd should use systemctl instead.

--list [name]

List all services or a specific service's runlevels

Specify which runlevels to affect (e.g., 2345)

Add a new service for management

Remove a service from management

Legacy tool for SysVinit systems. On systemd-based systems (CentOS 7+, RHEL 7+), use systemctl instead. Runlevels 0-6 have specific meanings: 0=halt, 1=single-user, 2-5=multi-user, 6=reboot.

chkconfig was developed by Red Hat for managing SysVinit services. With the adoption of systemd, its functionality has been largely replaced by systemctl, though it remains available for compatibility.

systemctl(1), service(8), update-rc.d(8)