chkconfig

chkconfig —  command is used to setup, view, or change services that are configured to start automatically during the system startup.

The Chkconfig command tool allows to configure services start and stop  automatically in the /etc/rd.d/init.d scripts through command line.

 

1. List All Services

Using ‘–list‘ parameter will displayed all services and their current start-up status in each run-level configuration.

[root@svr ~]# chkconfig --list

NetworkManager  0:off   1:off   2:on    3:on    4:on    5:on    6:off
abrt-ccpp       0:off   1:off   2:off   3:on    4:off   5:on    6:off
abrt-oops       0:off   1:off   2:off   3:on    4:off   5:on    6:off
...

2. Check Status of Specific Service

Below command shows startup configuration for a particular service. It’s showing HTTP services are turned off in all run levels.

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

3. How Do I Start a Particular Service on Run Levels

The following ‘chkconfig‘ command shows how we can start HTTP services only on run level 3 and 5 with ‘–level‘ parameter. First command starts httpd services on run level 3 and 5 and second command verifies the status of httpd services running on run level.

[root@svr ~]# chkconfig --level 35 httpd on
[root@svr ~]# chkconfig --list | grep httpd
httpd           0:off   1:off   2:off   3:on    4:off   5:on    6:off

4. How to Check Which Services are On/Off

The following command will display all the services which are On and Off in specific run level 5.

[root@svr ~]# chkconfig --list | grep 5:on
NetworkManager  0:off   1:off   2:on    3:on    4:on    5:on    6:off
abrt-ccpp       0:off   1:off   2:off   3:on    4:off   5:on    6:off
abrt-oops       0:off   1:off   2:off   3:on    4:off   5:on    6:off
abrtd           0:off   1:off   2:off   3:on    4:off   5:on    6:off
acpid           0:off   1:off   2:on    3:on    4:on    5:on    6:off
...
[root@svr ~]# chkconfig --list | grep 5:off
dnsmasq         0:off   1:off   2:off   3:off   4:off   5:off   6:off
dovecot         0:off   1:off   2:off   3:off   4:off   5:off   6:off
firstboot       0:off   1:off   2:off   3:off   4:off   5:off   6:off
kdump           0:off   1:off   2:off   3:off   4:off   5:off   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
nfs             0:off   1:off   2:off   3:off   4:off   5:off   6:off
...

5. How Do I Stop a Particular Service on Run Levels

The following command will turned Off a service called postfix for a just single run level. Similarly, we can turn Off a particular service in multiple run levels in one go as shown under.

[root@svr ~]# chkconfig --level 3 postfix off
[root@svr ~]# chkconfig --level 2345 postfix off

As we all know, there are seven run levels are available on Linux Operating System. We’ll cover the significant of different run levels and booting sequence in details in our upcoming article. So, please stay tuned.