How to manage installed services in Linux

Manage installed services in Linux

Services are programs or called daemon’s that once started run continuously in the background and are ready for input or monitor changes in your computer and respond to them. For example the Apache server has a daemon called httpd ( The d is for daemon ) that listens on port 80 your computer and when it receives a request for a page it sends the appropriate data back to the client machine.

Many services are required to run all the time however many can be safely turned of for both security reasons as running unnecessary services opens more doors into your computer, but also for performance reasons. It may not make much difference but your computer should boot slightly faster with less services it has to start on boot.

One of the techniques in every Linux administrators toolbox to improve security of a box is to turn off unneeded services.

Chkconfig and service Commands

There are 2 commands used to control services:

  • Service – This controls the starting and stopping of services during a session, these setting are not saved. If you start Apache this way but it is not set to start on boot using the above method then it will continue to run but on next boot will not start automatically.
  • Chkconfig – This controls which services are set to start on boot, by their nature these setting are saved and are applied at next boot. Changing these settings will not start the services immediately; it will just flag them to be strated from the next boot.

The command use for maintaining a service is

#service <name of the service> Status                     —        To check the status of the service

#service <name of the service> start                        —        To start the service

#service <name of the service> stop                         —        To stop a service

#service <name of the service> reload                     —        To reload the service

#service <name of the service> restart                    —        To restart the service

#service – – status-all                                                          —        To see all the service status

 

To command use for service availability is

#chkconfig – list                                             —        To check the availability of service

#chkconfig <service> on                               —        To make the service available after restart

#chkconfig <service> off                              —        To make the service unavailable after restart

 

Now we will see how to use the above commands:

Check the status of ftp service “vsftpd”

To check the status of the above service

#service vsftpd status

 

Start Ftp services

To start the ftp service, the command is

#service vsftpd start

 

Reload the ftp services, may be required after doing some change in config file.

To reload the service, the command is

#service vsftpd reload

 

To restart the ftp or any service, required when reload does not work

To restart the ftp services, the command will be

#service vsftpd restart

 

Check the status of the all service availability using chkconfig command.

To check the status of all service availability, use

#chkconfig –list

 

Note: where 0 1 2 3 4 5 6 are the run levels in Linux, The output shows that on which run level the service is available even after reboot.

 

How to check the status of a particular service, say “vsftpd”

To check the status of a vsftpd service, the command is

#chkconfig –list <name of the service>

#chkconfig –list vsftpd

 

Make the service availability on for vsftpd.

To make the service availability on for vsftpd service,

#chkconfig vsftpd on

 

Make the service availability off for vsftpd

To make the service availability off the command is

#chkconfig vsftpd off

 

How to make the service vsftpd availability on only runlevel 5

To make the service availability on, on a particular runlevel, the syntax is

#chkconfig –level <1-6> <service> <on/off>

#chkconfig – level 5 vsftpd on

 

The same can be done for making service unavailable in a particular run level.

 

I hope you enjoyed reading this article….

 

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