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|multiuser [NN | SS KK] update-rc.d [-n] name start|stop NN runlevel [runlevel]... . start|stop NN runlevel [runlevel]... . ... 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. Please note that this program was designed for use in package main‐ tainer scripts and, accordingly, has only the very limited functional‐ ity required by such scripts. System administrators are not encour‐ aged 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 instead. INSTALLING INIT SCRIPT LINKS When run with either the defaults, multiuser, start, or stop options, update-rc.d makes links /etc/rcrunlevel.d/[SK]NNname that point to the script /etc/init.d/name. 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 installed before. 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 ser‐ vice in runlevels 2345 and to stop the service in runlevels 016. If multiuser is used then update-rc.d will make links to start the ser‐ vice in runlevels 2345 and top stop the service in only runlevel 1. By default all the links will have sequence number 20, but this can be overridden by supplying one NN or two SS and KK arguments to either defaults or multiuser; a single argument overrides the sequence number for both start and stop links whereas a pair of arguments overrides the sequence numbers for start and stop links, respectively. As a rule of thumb, the sequence number of the stop link should 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 or multiuser 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 run‐ level numbers. The set is terminated by a solitary full stop charac‐ ter. 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 run‐ level is named in multiple sets then only the last one counts. There‐ fore it is not possible to create multiple start or multiple stop links for a service in a single runlevel directory. 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. 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 Equivalent command using explicit argument sets: update-rc.d foobar start 20 2 3 4 5 . stop 20 0 1 6 . Insert links for a service that should be running during multi-user mode, but that does not need to be explicitly stopped on shutdown: update-rc.d foobar multiuser Equivalent command using explicit argument sets: update-rc.d foobar start 20 2 3 4 5 . stop 20 1 . More typical command using explicit argument sets: update-rc.d foobar start 30 2 3 4 5 . stop 70 0 1 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 -f foobar remove update-rc.d foobar stop 20 2 3 4 5 . Example of a command for installing a system initialization-and-shut‐ down script: update-rc.d foobar start 45 S . start 31 0 6 . Example of a command for disabling a system initialization-and-shut‐ down script: update-rc.d -f foobar remove update-rc.d foobar stop 45 S . NOTES The multiuser option is an Ubuntu-extension intended to reduce the amount of time spent stopping services during shutdown and reboot that have no particular requirement to be explicitly stopped. Unless your init script does something in the stop command that is more than just sending the TERM or KILL signal to the running process, you should strongly consider using multiuser instead of defaults. 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, sysv-rc-conf(8), bum(8), init(8). Debian Project 14 November 2005 UPDATE-RC.D(8)