2.4.3 Customizing runlevels
Customizing runlevels is an advanced system administration task. The following
advice holds for most services.
To enable service service in runlevel R create the
symbolic link
/etc/rcR.d/Sxyservice with target
../init.d/service. The sequence number xy
should be the sequence number that was assigned to the service when the package
was installed.
To disable the service, rename the symbolic link so that its name begins with a
K instead of with an S and its sequence number is 100
minus xy.
It is convenient to use a runlevel editor such as sysv-rc-conf or
ksysv for these purposes.
It is possible to delete the S symlink for a service in a
particular runlevel directory instead of renaming it. This does not disable
the service but leaves it in a "floating" state as far as the
sysv-rc init system is concerned: on runlevel changes the service
will be neither started nor stopped but will be left as it was, whether running
or not running. Note, however, that a service left in such a floating state
will be started if its package is upgraded whether or not it was running before
the upgrade. This is a known shortcoming of the current Debian system. Note
also that you should retain a service's K symlinks in runlevels 0
and 6. If you delete all the symlinks for a service then on upgrade the
service's package will restore the symlinks to their factory default state.
It is not advisable to make any changes to symlinks in
/etc/rcS.d/.
