update-rc.d Man page

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

NAME

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

SYNOPSIS

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

update-rc.d [-n] name defaults

update-rc.d [-n] name disable|enable [ S|2|3|4|5 ]

DESCRIPTION

update-rc.d updates the System V style init script links /etc/rcrun‐
level.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.

INSTALLING INIT SCRIPT LINKS
update-rc.d requires dependency and runlevel information to be provided
in the init.d script LSB comment header of all init.d scripts. See the
insserv(8) manual page for details about the LSB header format.

When run with the defaults option, update-rc.d makes links named
/etc/rcrunlevel.d/[SK]NNname that point to the script /etc/init.d/name,
using runlevel and dependency information from the init.d script LSB
comment header.

If any files named /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 cus‐
tomized 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 installed before.

Older versions of update-rc.d also supported start and stop options.
These options are no longer supported, and are now equivalent to the
defaults option.

A common system administration error is to delete the links with the
thought that this will “disable” the service, i.e., that this will pre‐
vent 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.

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

REMOVING SCRIPTS
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/rcrun‐
level.d directories that are not symbolic links to the script
/etc/init.d/name will be left untouched.

DISABLING INIT SCRIPT START LINKS
When run with the disable [ S|2|3|4|5 ] options, update-rc.d modifies
existing runlevel links for the script /etc/init.d/name by renaming
start links to stop links with a sequence number equal to the differ‐
ence of 100 minus the original sequence number.

When run with the enable [ S|2|3|4|5 ] options, update-rc.d modifies
existing runlevel links for the script /etc/init.d/name by renaming
stop links to start links with a sequence number equal to the positive
difference of current sequence number minus 100, thus returning to the
original sequence number that the script had been installed with before
disabling it.

Both of these options only operate on start runlevel links of S, 2, 3,
4 or 5. If no start runlevel is specified after the disable or enable
keywords, the script will attempt to modify links in all start run‐
levels.

OPTIONS

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

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

EXAMPLES
Insert links using the defaults:
update-rc.d foobar defaults
The equivalent dependency header would have start and stop
dependencies on $remote_fs and $syslog, and start in
runlevels 2-5 and stop in runlevels 0, 1 and 6.
Remove all links for a script (assuming foobar has been deleted
already):
update-rc.d foobar remove
Example of disabling a service:
update-rc.d foobar disable
Example of a command for installing a system initialization-and-shut‐
down script:
update-rc.d foobar defaults
Example of a command for disabling a system initialization-and-shutdown
script:
update-rc.d foobar disable

BUGS

See http://bugs.debian.org/sysv-rc.

FILES
/etc/init.d/
The directory containing the actual init scripts.

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

/etc/init.d/skeleton
Model for use by writers of init.d scripts.

SEE ALSO

Debian Policy Manual,
/etc/init.d/skeleton,
insserv(8), sysv-rc-conf(8), bum(8), init(8).

Debian Project 14 November 2005 UPDATE-RC.D(8)