Chapter 9. The Operating System

67

The system administrator will have the opportunity to customize runlevels by simply adding,

moving, or removing the symbolic links in

/etc/rc

n

.d

if symbolic links are being used, or

by modifying

/etc/runlevel.conf

if the

file rc

method is being used.

To get the default behavior for your package, put in your

postinst

script

update rc.d

package

defaults

and in your

postrm

if [ "$1" = purge ]; then

update rc.d

package

remove

fi

. Note that if your package changes runlevels or priority, you may have to remove and

recreate the links, since otherwise the old links may persist. Refer to the documentation of

update rc.d

.

This will use a default sequence number of 20. If it does not matter when or in which order the

init.d

script is run, use this default. If it does, then you should talk to the maintainer of the

sysvinit

package or post to

debian devel

, and they will help you choose a number.

For more information about using

update rc.d

,

please consult its man page

update rc.d(8)

.

Running initscripts

The program

invoke rc.d

is provided to make it easier for package maintainers to properly

invoke an initscript, obeying runlevel and other locally defined constraints that might limit a

package's right to start, stop and otherwise manage services. This program may be used by

maintainers in their packages' scripts.

The use of

invoke rc.d

to invoke the

/etc/init.d/*

initscripts is strongly recom 

mended

1

, instead of calling them directly.

By default,

invoke rc.d

will pass any action requests (start, stop, reload, restart. . . ) to the

/etc/init.d

script, filtering out requests to start or restart a service out of its intended run 

levels.

Most packages will simply need to change:

/etc/init.d/

in their

postinst

and

prerm

scripts to:

if which invoke rc.d >/dev/null 2>&1; then

invoke rc.d

package

else

/etc/init.d/

package

fi

1

In the future, the use of invoke rc.d to invoke initscripts shall be made mandatory. Maintainers are advised to

switch to invoke rc.d as soon as possible.