Tyler Chris - Fedora Linux стр 36.

4.5.4. Where Can I Learn More?

4.6. Managing and Configuring Services

Each service consumes memory and processor time, and each network service may provide a weak spot for an attack against your system. Disabling unused services can reduce your boot time, speed up your system, and reduce your security risk.

4.6.1. How Do I Do That?

Figure 4-6. Services configuration window

The configuration of the current runlevel is shown by default. Every service with a checkmark in front of it will be started when that runlevel is entered; to add or clear a checkmark, click on the checkbox.

Click on a service name to see a description of that service and its current status ( running or stopped ). Click on the Save icon (or FileSave Changes) when you've configured the services to your liking; your changes will take effect next time you change runlevels or boot the system.

You can edit the settings for another runlevel (3, 4, 5, or all three at the same time) using options on the Edit Runlevel menu.

To start, stop, or restart a service immediately, regardless of whether it's configured to start automatically at boot time, click on the service name and then click on the Start, Stop, or Restart icon.

4.6.1.1. Configuring services using a character user interface

# ntsysv

This will configure the current runlevel. To configure a different runlevel, use the --level option:

# ntsysv --level 4

The display shown in Figure 4-7 will

appear.

Figure 4-7. The ntsysv display

Use the arrow keys to select a service, the spacebar to check/uncheck a service, and Tab to switch between the service list and the buttons. When you are done, press Tab to advance to the OK button and then press Enter.

4.6.1.2. Configuring services from the command line

$ chkconfig --list

NetworkManager 0:off 1:off 2:off 3:off 4:off 5:off 6:off

NetworkManagerDispatcher 0:off 1:off 2:off 3:off 4:off 5:off 6:off

acpid 0:off 1:off 2:off 3:on 4:on 5:on 6:off

amd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

anacron 0:off 1:off 2:on 3:on 4:on 5:on 6:off

apmd 0:off 1:off 2:on 3:on 4:on 5:on 6:off

arptables_jf 0:off 1:off 2:on 3:on 4:on 5:on 6:off

...(Lines snipped)...

If you specify a service name, then only the configuration for that service is shown:

$ chkconfig --list httpd

httpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

Note that each of the seven runlevels is shown, even though the configurations for runlevels 0 and 6 are ignored except for K files (since 0 is halt and 6 is reboot).

To enable a service in a runlevel, use the --level option to specify the runlevel along with the on argument:

# chkconfig --level 4 httpdon

# chkconfig --list httpd

httpd 0:off 1:off 2:off 3:off 4:on 5:off 6:off

To disable it, use the off argument:

# chkconfig --level 4 httpdoff

# chkconfig --list httpd

httpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

To reset a service to its default configuration, use the reset argument. The configuration will be reset for the runlevel you specify, or for all runlevels if you don't include a - -level option:

# chkconfig --level4 httpdreset

# chkconfig httpdreset

4.6.1.3. Managing services from the command line

start

Start the service. This will fail if the service is already running.

stop

Stop the service. This will fail if the service is not running.

restart

Restart the service by stopping it and then starting it.

reload

Reload the configuration files for the service after they have been edited.

status

Display the current status of the service. This will indicate if the service is stopped or running; depending on the service, additional information may be displayed.

For example, to start the web service (named httpd ):

# servicehttpdstart

Starting httpd: [ OK ]

You can then check its status:

# servicehttpdstatus

httpd (pid 13154 13153 13152 13151 13150 13149 13148 13147 13117) is running...

The pid values printed are the process IDs of the web server processes.

To make the web server reload its configuration file after it's been edited:

# servicehttpdreload

Reloading httpd: [ OK ]

Finally, to stop the web server:

# servicehttpdstop

Stopping httpd: [ OK ]

4.6.2. How Does It Work?

In an age of viruses, worms, and identity theft, keeping information private and secure has taken on great importance. Managing user identity creates the framework for system securityeven on a single-user system, where a distinction is maintained between using the system as the normal user and using the system as the root user.

4.7.1. How Do I Do That?

For example, company employee Richard might be all of the following:

A member of the IT department

Located at the company's Toronto office

The leader of the team putting together the big sales pitch to Acme, Ltd.

Part of the Christmas party committee

A player in the Tuesday evening company soccer league

(And that doesn't even touch on life outside of the company!)