Ubuntu Manpage: update-rc.d - install and remove System-V style init script links

Provided by: init-system-helpers_1.57_all

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
       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 disabled (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 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.

AUTHOR

       Ian Jackson, Miquel van Smoorenburg

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

COPYRIGHT

       2001 Henrique de Moraes Holschuh