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''?
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 /etc/init.d/name.
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.
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.
Debian Policy Manual, /etc/init.d/skeleton, init(8).
2 pages link to update-rc.d(8):
