UPDATE-RC.D(8) sysv-rc UPDATE-RC.D(8)

update-rc.d - install and remove System-V style init script links

update-rc.d [-n] [-f] name remove

update-rc.d [-n] name defaults [NN | NN-start NN-stop]

update-rc.d [-n] name start|stop NN runlevel runlevel ... . start|stop NN runlevel runlevel ... . .

update-rc.d automatically updates the System V style init script links /etc/rcrunlevel.d/NNname to scripts /etc/init.d/name. These are run by
init when changing runlevels and are generally used to start and stop system services such as daemons. runlevel is one of the runlevels supported
by init, 0123456789S, and NN is the two-digit sequence code used by init to decide which order to run the scripts in.

This manpage documents only the usage and behaviour of update-rc.d. For a discussion of the System V style init script arrangements please see
init(8) and the Debian Policy Manual.

When run with either the defaults, start, or stop options, update-rc.d makes links /etc/rcrunlevel.d/[SK]NNname pointing to the script

If any files /etc/rcrunlevel.d/[SK]??name already exist then update-rc.d does nothing. This is so that the system administrator can rearrange the
links, provided that they leave at least one link remaining, without having their configuration overwritten.

If defaults is used then update-rc.d will make links to start the service in runlevels 2345 and stop the service in runlevels 016. By default all
the links will have sequence code 20, but this can be overridden by supplying one or two NN arguments; one argument overrides the sequence code
for both start and stop links whereas of two arguments the first overrides the code for start links and the second that for stop links.

Instead of defaults the runlevels in which to start and stop the service may be specified explicitly using a series of sets of arguments:

Each of these sets starts with an argument start or stop to specify whether start or stop links are to be created by that set. Then follows NN,
the sequence code number for all the links in the set, and one or more runlevel numbers as a single argument each. The set is terminated by an
argument . (a single full stop).

When explicit specification, rather than defaults, is used there will usually be one start and one stop set. If different sequence codes are
required in different runlevels then several start sets or several stop sets may be specified.

The script /etc/init.d/name must exist before update-rc.d is run to create the links.

When invoked with the remove option, update-rc.d removes any links in the /etc/rcrunlevel.d directories to the script /etc/init.d/name. The
script must have been deleted already - update-rc.d checks for this. update-rc.d is usually called from a package's post-removal script when that
script detects that its first argument is purge, indicating that the user has requested the configuration for the package to be removed. Any
files in the /etc/rcrunlevel.d directories that are not symbolic links to the script /etc/init.d/name will be left untouched.

-n Don't do anything, just show what we would do.

-f Force removal of symlinks even if /etc/init.d/name still exists.

Insert links using the defaults:
update-rc.d foobar defaults
Equivalent command using explicit argument sets:
update-rc.d foobar start 20 2 3 4 5 . stop 20 0 1 6 .
There should be a way for the system administrator to specify at least the default start and stop runlevels to be used by defaults and possibly to
override other things as well.

The directory containing the actual init scripts.

The directories containing the links used by init and managed by update-rc.d.

Model for use by writers of init.d scripts.