Gerard Beekmans gerard at
Tue Jan 23 09:25:45 PST 2001

On January 23, 2001 04:45 am, Jan Stifter wrote:
> can anybody explain me the following lines from inittab?
> f1:0:respawn:/sbin/sulogin
> f2:6:respawn:/sbin/sulogin
> su:S1:respawn:/sbin/sulogin
> why does runlevel 0, 6 and S need a /sbin/sulogin ?

you change to runlevel 0 or 6 and at the end the rc script is supposed to run 
/etc/rc0.d/S99halt or /etc/rc6.d/S99reboot

But scripts can have bugs, symlinks may be wrong/missing so those scripts 
aren't run and the system will just 'sit' there. That's when the fallthrough 
lines are read (when rc's done in level 0 or 6 a reboot/halt should take 
place but in case that doens't happen init just goes on with inittab and 
executes all that's remaining) which is sulogin. This way you can get a root 
shell and issue the halt or reboot command manually.

The reason why levels S and 1 have sulogin is that those levels don't spawn 
agetty (they're not supposed to, it's not multi-user but single-user). It are 
single user modes, single being root only. So we get the user a root shell 
through sulogin

Gerard Beekmans

-*- If Linux doesn't have the solution, you have the wrong problem -*-

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