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The chkconfig command and SysV start-up scripts
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-IAN! idallen@idallen.ca

In this file:
    # chkconfig --list
    # chkconfig nntp reset

Linux SysV-style service start-up scripts are kept in directory
/etc/init.d/ (or in /etc/rc.d/init.d/).  Symbolic links to these
scripts are placed in directory /etc/rc?.d/ (or in /etc/rc.d/rc?.d/).
The symbolic links starting with "S" and a number start a service;
the symbolic links starting with "K" and a number stop ("kill") a service.

A service is started in a run level by calling its SysV start-up script
with a single argument of "start".  A service is stopped in a run level
by calling its SysV start-up script with a single argument of "stop".
Most run-level changes happen at boot time and shut down, though you
can use the "telinit" command to change run levels any time.

While is is always possible to create and remove the symbolic links in
the rc?.d directories by hand (using "ln -s" and "rm"), the chkconfig
command is a handy tool for listing and manipulating these symbolic
links in their run level directories.

The chkconfig output consists of a list of the services found in
the init.d directory, followed by a separate list of the services
controlled by the xinetd "super-server" (under the title line "xinetd
based services").

Below are a list of the common uses of chkconfig.

Find out all the services that are installed (but that may or may not
be configured to start in some run level):

    # chkconfig --list
    httpd           0:off   1:off   2:off   3:on    4:on    5:on    6:off
    alsa            0:off   1:off   2:off   3:on    4:off   5:on    6:off
    ...
        hotwayd:        on
        proftpd-xinetd: off
        saned:  on


Find out which services are enabled to start in at least one run level:

    # chkconfig --list | grep :on | sort
    alsa            0:off   1:off   2:on    3:on    4:on    5:on    6:off
    crond           0:off   1:off   2:on    3:on    4:on    5:on    6:off
    ...
    xfs             0:off   1:off   2:on    3:on    4:on    5:on    6:off
    xinetd          0:off   1:off   2:off   3:on    4:on    5:on    6:off

List a particular service:

    # chkconfig --list network
    network      0:off   1:off   2:on    3:on    4:on    5:on    6:off

--------------------------------
Resetting symlinks for a service
--------------------------------

Many/most of the SysV start-up scripts contain a "chkconfig" comment line
in the comments at the start of the script.  The comment line might look
something like this:

    # chkconfig: 2345 55 10

The above shell comment line is readable by "chkconfig" if you give
chkconfig the "reset" option for that service.  With "reset", chkconfig
will automatically create start/stop symlinks in run levels 2,3,4,5
at priority 55 and 10 if you use this chkconfig command line as root.
For example:

    bash# chkconfig ntpd reset

Now "chkconfig --list" will show ntpd enabled in run levels 2,3,4,5.
It will start at priority 55 and stop at priority 10.

Note: You can always add the appropriate start/stop ntpd symlinks manually
in the rc?.d directories if the above procedure isn't possible because
the chkconfig command is missing.  Don't depend on chkconfig!