System administrations

Services can be controlled by three programs in linux.

  • chkconfig (command line only)
  • ntsysv (simple text-based application that doesn't require a graphical desktop)
  • or the Service Configuration Tool (graphical application).

It's generally fastest way to control services at the command line. The chkconfig command gives you a simple way to maintain different runlevels within the /etc/rc.d directory structure. With chkconfig, you can add, remove, and change services; list startup information; and check the state of a particular service.

The chkconfig command can be used to configure runlevels and list the current runlevel configuration. It must be run as root if modifying a runlevel. Otherwise commands such as listing whether a service is started at boot time can be run as a non-root user.

--level runlevel

Specifies a runlevel to turn on, turn off, or reset a service.

--list service

Lists startup information for services at different runlevels. services are just on or off. With no argument, all services are listed.

--add service

Adds a service, creating links in the default specified runlevels (or all runlevels, if none are specified).

--del service

Deletes all links for the service (startup and shutdown) in all runlevel directories.

service on

Turns a service on, creating a service link in the specified or default runlevel directories

service off

Turns a service off, creating shutdown links in specified or default directories.

service reset

Resets service startup information, creating default links as specified in the chkconfig entry in the service's init.d service script.

To Know about all available switches with chkconfig commands use --help options
chkconfig help

To check the status of all services on all runlevel use --list switch with |more options
chkconfig list more

To check the status of all services on runlevel one use --list switch with |more options
chkconfig list level one

To check the status of only vsftpd services on all runlevel one use --list switch with service name
chkconfig list vsftpd

To on off vsftpd service on runlevel use on off switch
chkconfig on off switch

To deleted vsftpd service use del switch ( Note that only service will be delete, not rpm you can add this service again without installing rpm again )
chkconfig del switch

To add service use add switch ( Note rpm must be install first )
chkconfig add switch

The Text Console Service Configuration Tool

If you're managing a large number of services, the command line can be less efficient. You don't need a GUI, just the ntsysv tool, which you can open with the command of the same name. However, it affects only services in the current runlevel unless you add an appropriate switch.

For example, if you want to activate several services in runlevels 3 and 5, start ntsysv with the following command:

 # ntsysv --level 3 5