Provided by: sysv-rc_2.86.ds1-59ubuntu13_all
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 | SS KK]
update-rc.d [-n] name start|stop NN runlevel [runlevel]... .
start|stop NN runlevel [runlevel]... . ...
update-rc.d updates the System V style init script links
/etc/rcrunlevel.d/NNname whose target is the script /etc/init.d/name.
These links are run by init when it changes runlevels; they are
generally used to start and stop system services such as daemons.
runlevel is one of the runlevels supported by init, namely,
0123456789S, and NN is the two-digit sequence number that determines
where in the sequence init will run the scripts.
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.
Please note that this program was designed for use in package
maintainer scripts and, accordingly, has only the very limited
functionality required by such scripts. System administrators are not
encouraged to use update-rc.d to manage runlevels. They should edit
the links directly or use runlevel editors such as sysv-rc-conf and bum
INSTALLING INIT SCRIPT LINKS
When run with either the defaults, start, or stop options, update-rc.d
makes links /etc/rcrunlevel.d/[SK]NNname that point to the script
If any files /etc/rcrunlevel.d/[SK]??name already exist then update-
rc.d does nothing. The program was written this way so that it will
never change an existing configuration, which may have been customized
by the system administrator. The program will only install links if
none are present, i.e., if it appears that the service has never been
A common system administration error is to delete the links with the
thought that this will "disable" the service, i.e., that this will
prevent the service from being started. However, if all links have
been deleted then the next time the package is upgraded, the package’s
postinst script will run update-rc.d again and this will reinstall
links at their factory default locations. The correct way to disable
services is to configure the service as stopped in all runlevels in
which it is started by default. In the System V init system this means
renaming the service’s symbolic links from S to K.
If defaults is used then update-rc.d will make links to start the
service in runlevels 2345 and to stop the service in runlevels 016
unless an LSB-style header is present in the init.d script and the
/etc/update-rc.d-lsbparse file exist. If such header exist, the levels
listed in the Default-Start and Default-Stop fields in that header are
used instead. By default all the links will have sequence number 20,
but this should be overridden if there are dependencies. For example if
daemon B depends on A, then A must be started before B and B must be
killed before A. You accomplish this by supplying two NN arguments. In
general, core daemons should start early and be killed late, whilst
applications can start late and be killed early. See EXAMPLES below.
The first NN argument supplies the start sequence number and the second
NN argument supplies the kill sequence number. Kill scripts are called
first, passing a stop argument. Then start scripts are called passing a
start argument. In either case, calls happen in ascending sequence
Supplying a single NN argument will use the same number for both start
and kill links. This is supported for backward compatibility but is
discouraged, as it may lead to inconsistent settings. As a rule of
thumb, if you increase the start sequence number you should also
decrease the stop sequence number, and vice-versa.
As a rule of thumb, the sequence number of the stop link should be 100
minus the sequence number of the start link; this causes services to be
stopped in the opposite order to that in which they are started.
Obviously, therefore, the default stop sequence number should be 80.
Defaulting to 20, as update-rc.d does, is an old bug that cannot be
fixed because of the risk of breaking things.
Instead of defaults one can give one or more sets of arguments
specifying particular runlevels in which to start or stop the service.
Each of these sets of arguments starts with the keyword start or stop
and a sequence number NN, followed by one or more runlevel numbers.
The set is terminated by a solitary full stop character. 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. If this is done and the same runlevel is named in multiple
sets then only the last one counts. Therefore it is not possible to
create multiple start or multiple stop links for a service in a single
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. If the script is still present
then update-rc.d aborts with an error message.
update-rc.d is usually called from a package’s post-removal script when
that script is given the purge argument. 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 .
More typical command using explicit argument sets:
update-rc.d foobar start 30 2 3 4 5 . stop 70 0 1 6 .
Insert links at default runlevels when B requires A
update-rc.d script_for_A defaults 80 20
update-rc.d script_for_B defaults 90 10
Insert a link to a service that (presumably) will not be needed by any
update-rc.d top_level_app defaults 98 02
Insert links for a script that requires services that start/stop at
sequence number 20
update-rc.d script_depends_on_svc20 defaults 21 19
Remove all links for a script (assuming foobar has been deleted
update-rc.d foobar remove
Example of disabling a service:
update-rc.d -f foobar remove
update-rc.d foobar stop 20 2 3 4 5 .
Example of a command for installing a system initialization-and-
update-rc.d foobar start 45 S . stop 31 0 6 .
Example of a command for disabling a system initialization-and-shutdown
update-rc.d -f foobar remove
update-rc.d foobar stop 45 S .
The directory containing the actual init scripts.
The directories containing the links used by init and managed by
Model for use by writers of init.d scripts.
Debian Policy Manual,
sysv-rc-conf(8), bum(8), init(8).