What is it? (was Re: Current Run-Level: How can you tell?)

[L. Hirschbiegel]

In article <1991May3.185400.4685 at ico.isc.com> rcd at ico.isc.com (Dick Dunn) writes:
>alan at ukpoit.co.uk (Alan Barclay) writes about run levels:
>
>> As with most unix things it really depends on how you've configured it
>
   [ text deleted ]
>
>> 0 == Single user
>More conventionally, 0 is shutdown.
>
>> 1 == Multi user (no networking)
>If 0 is used for shutdown, 1 is normally single-user, and 2 is multi-user
>with no networking; then
>> 3 == Multi user (with networking)
>as Alan says.
>
>> 6 == Shutdown
>More conventionally, 6 is shutdown and reboot.
>-- 
>Dick Dunn     rcd at ico.isc.com -or- ico!rcd       Boulder, CO   (303)449-2870
>   ...If you plant ice, you're gonna harvest wind.


Its even more complicated under SystemV. From my manual pages for "init":

SYNOPSIS
			   /etc/init [0123456SsQqabc]

There are also pseudostates a, b and c, which may be defined to run certain
commands, but which do not cause the current runlevel to change.
Sounds like an indexed runlevel to me :-) [ init 3.a ...]
In addition there is a substantial diffence under SysV for runlevel 1 and
runlevel S (both switch to single user state). Runlevel 1 can only be called
from the system console (/dev/console, that is) and unmounts all filesystems
except root.
Runlevel S will keep all mounted filesystems and can be (in theory) called
from any terminal. This terminal will then become the new system console.
The biggest difference between runlevel 1 and S: in level 1 all processes
not associated to the (real) system console will be killed, in level S
only processes spawned by "init" are killed...

Lothar Hirschbiegel

-- 
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| L. Hirschbiegel, AEG - A84, Frankfurt (Germany) |
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