> On Wed, 08 May 2024, Steve Litt wrote:
> >I'm not familiar with /etc/rcS.
> Typically, rcS.d are software or services that are started in addition of
> whichever runlevel is selected. They're generally tasks that any runlevel
> depends on, like mounting file systems, or enabling the network, or even
> loading kernel modules.

You missed the context, /etc/rcS for busybox init is not the same thing
as /etc/rcS.d/ in sysv init.

Busybox init doesn't have runlevels which sysv init has, so for busybox
there is just one startup script and it usually named /etc/rcS, while
sysv has one (which starts/stops /etc/rcN.d/ scripts) for each runlevel.

So /etc/inittab for sysv is like:
si::sysinit:/etc/init.d/rcS
l0:0:wait:/etc/init.d/rc 0
l1:1:wait:/etc/init.d/rc 1
l2:2:wait:/etc/init.d/rc 2
l3:3:wait:/etc/init.d/rc 3
l4:4:wait:/etc/init.d/rc 4
l5:5:wait:/etc/init.d/rc 5
l6:6:wait:/etc/init.d/rc 6
where /etc/init.d/rcS is "exec /etc/init.d/rc S".

while busybox inittab is like:
::sysinit:/etc/rcS

Regards,
/Karl Hammar