runlevel.conf - The file-rc runlevel configuration file
is the configuration file for the package file-rc
(8) boot concept. While the SysV init scheme implements
runlevels through symlinks in /etc/rc?.d/*
uses only one file runlevel.conf
to replace all these
This file consists of 4 columns separated by TABs or spaces with the following
- The first column is the sort criteria for starting and
stopping the scripts.
- The second column consists of a comma-separated list of
runlevels in which the script should be switched `off' or a single
`-' if the script should never be stopped (within that
- The third column consists of a comma-separated list of
runlevels in which the script should be switched `on' or a single
`-' if the script should never be started (with that
- The last column specifies the full name of the script.
Lines beginning with `#
' and empty lines are ignored.
All scripts executed by the init system are located in /etc/init.d
If a scripts has the .sh
suffix it is a bourne shell script and MAY be
handled in an optimized manner. The behaviour of executing script in an
optimized way will not differ in any way from it being forked and executed in
the regular way.
The following runlevels are defined:
- System bootup (NONE).
- Single user mode (not to be switched to directly)
- single user mode
- multi user mode
When the systems boots, the lines with 'S
' in the third column are
executed. It in turn executes all these scripts in alphabetical (and thus
numerical) order. The first argument passed to the executed scripts is
. The runlevel at this point is 'N
Only things that need to be run once to get the system in a consistent state are
to be run. The 'S
' state is NOT meant to replace rc.local
should not start daemons in this runlevel unless absolutely necessary. Eg, NFS
might need the portmapper, so it is OK to start it early in the bootprocess.
But this is not the time to start the squid proxy server.
After the 'S
' scripts have been executed, init switches to the default
runlevel as specified in /etc/inittab
, usually '2
(8) then executes the /etc/init.d/rc
script which takes care
of starting the services with '2
' in the third column.
Because the previous runlevel is 'N
' (none) the scripts with '2
in the second column will NOT be executed - there is nothing to stop yet, the
system is busy coming up.
If for example there is a service that wants to run in runlevel 4 and ONLY in
that level, it will place '2,3,5
' in the second column to stop the
service when switching out of runlevel 4. We do not need to run that script at
The scripts will be executed in alphabetical order, with the first argument set
When one switches from (for example) runlevel 2 to runlevel 3,
will first execute in alphabetical order all scripts
' in the second column with 'stop
' as first argument and
then all scripts with '3
' in the third column with 'start
As an optimization, a check is made for each "service" to see if it
was already running in the previous runlevel. If it was, and there is no entry
present in the second column for the new runlevel, there is no need to start
it a second time so that will not be done.
On the other hand, if there was an entry in the second column, it is assumed the
service was stopped on purpose first and so needs to be restarted.
We MIGHT make the same optimization for stop scripts as well - if no entry in
the third column was present in the previous runlevel, we can assume that
service was not running and we don't need to stop it either. In that case we
can remove the "coming from level N" special case mentioned above.
But right now that has not been implemented.
Switching to single user mode is done by switching to runlevel 1. That will
cause all services to be stopped (assuming they all have '1
' in the
second column). The runlevel 1 scripts will then switch to runlevel 'S
which has no scripts - all it does is spawn a shell directly on
Going to runlevel 0 or 6 will cause the system to be halted or rebooted,
respectively. For example, if we go to runlevel 6 (reboot) first all scripts
' in the second column will be executed alphabetically with
' as the first argument.
Then the scripts with '6
' in the third column will be executed
alphabetically with 'stop
' as the first argument as well. The reason is
that there is nothing to start anymore at this point - all scripts that are
run are meant to bring the system down.
#<sort> <off> <on> <script>
05 - 0 /etc/init.d/halt
05 - 1 /etc/init.d/single
05 - 6 /etc/init.d/reboot
10 0,1,6 2,3,4,5 /etc/init.d/sysklogd
12 0,1,6 2,3,4,5 /etc/init.d/kerneld
89 0,1,6 2,3,4,5 /etc/init.d/cron
99 - 2,3,4,5 /etc/init.d/rmnologin
99 0,1,6 2,3,4,5 /etc/init.d/xdm
was originally written by Winfried Trümper
<email@example.com> and adapted to the Debian system by Tom Lees
<firstname.lastname@example.org>, Martin Schulze <email@example.com> and
Roland Rosenfeld <firstname.lastname@example.org>.
This man page was written by Roland Rosenfeld <email@example.com>.