INVOKE-RC.D(8) Debian GNU/Linux INVOKE-RC.D(8)
NAME
invoke-rc.d - install and remove System-V style init script links
SYNOPSIS
update-rc.d [-f] name remove
update-rc.d name defaults
update-rc.d name defaults-disabled
update-rc.d name disable|enable [ S|2|3|4|5 ]
DESCRIPTION
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.
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.
When run with the defaults-disabled option, update-rc.d makes links named /etc/rcrunlevel.d/KNNname that point to the script
/etc/init.d/name, using dependency information from the init.d script LSB comment header. This means that the init.d script will be dis-
abled (see below).
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 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 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
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.
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/rcrunlevel.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 difference 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 runlevels.
OPTIONS
-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-shutdown 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)
AUTHOR
Ian Jackson, Miquel van Smoorenburg
Licence: GNU Public Licence v2 or Later (GPLv2+)
COPYRIGHT
2001 Hernique Holschuh
14 November 2005 INVOKE-RC.D(8)