Having identified, and possibly changed the
runlevel your system will boot to you
can now control which services you want to be automatically started at
boot
time. As mentioned previously it is important to avoid having any
services running that you don't actually need. Every server is a
potential access point into your Linux server so it is good practice to
turn off anything you don't think you will use. Bear in mind that you
can always turn on a service at a later date if you find you need it.
There are number of ways to control what services get started using
both
command line and graphical tools without having to delve into the
depths of
your Linux system.
The command line tool chkconfig (usually located in /sbin) can be used
to list
and configure which services get started at boot time. To list all
service
settings run the following command:
/sbin/chkconfig
--list
This will display a long list of services showing whether or not they
are
started up at various runlevels. You may want to narrow the search down
using
Linux grep command. For example to list the entry for the HTTP daemon
you would
do the following:
/sbin/chkconfig
--list | grep httpd
which should result in something like:
httpd
0:off 1:off 2:off
3:on
4:off 5:off 6:off
Alternatively you may just be interested to know what gets started for
runlevel
3:
/sbin/chkconfig
--list | grep '3:on'
chkconfig can also be used to change the settings. If we wanted the
HTTP
service to start up when we at runlevel 5 we would issue the following
command:
/sbin/chkconfig
--level 5 httpd on
A number of graphical tools are also available for administering
services. On
RedHat 9 you can run the following command:
redhat-config-services
The equivalent command on RedHat Fedora Core is:
system-config-services
The above graphical tools allow you to view which services will start
for each
runlevel, add or remove services for each runlevel and also manually
start or
stop services.
Another useful tool if you do not have a graphical desktop running or
access
via a remote X server is the ntsysv command. ntsysv resides in
/sbin on
most systems. Whilst a convenient tool when you don't have an X server
running
the one draw back of ntsysv is that it only allows you to change the
settings
for the current runlevel.
