update-rc.d(8) - phpMan

UPDATE-RC.D(8) Debian GNU/Linux UPDATE-RC.D(8)

NAME
update-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 run-
levels; they are generally used to start and stop system services such as daemons. run-
level 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 Man-
ual.

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 de-
tails about the LSB header format.

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

When run with the defaults-disabled option, update-rc.d makes links named /etc/rcrun-
level.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 noth-
ing. The program was written this way so that it will never change an existing configura-
tion, 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 in-
stalled 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/rcrun-
level.d directories to the script /etc/init.d/name. The script must have been deleted al-
ready. 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 se-
quence 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 se-
quence 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 and http://bugs.debian.org/init-system-helpers.

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),
init(8)

AUTHOR
Ian Jackson, Miquel van Smoorenburg

Licence: GNU Public Licence v2 or Later (GPLv2+)

14 November 2005 UPDATE-RC.D(8)

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