On Sat, Aug 09, 2014 at 01:02 PM, Rieker Flaik said:
> There I can exec busybox its normal init "/sbin/init". This is
> what I want to use in this pre-OS, having a nice init system to
> spawn all kinds of programs like udhcp and dropbear to do the
> backup stuff.
It is actually very easy to get control back from /sbin/init.
Replace /sbin/init with the script you want to run. Then run the
command:
telinit u
This tells the init process to shutdown and restart. When it
restarts, your script at /sbin/init is what will run.
Before you start playing with this, do:
sudo ls -l /proc/1/fd
and notice that most standard IO is turned off (at least on my
systems). If you want PID-1 to be a shell again then you will
need to reconnect some IO.
Some LiveCD/USB systems use this trick to get PID-1 to run from a
small (RAM based) busybox system during shutdown. The great
thing about this is it gives you the ability to have shell access
throughout the shutdown process even after all non-RAM file
systems have been unmounted.
IMO this is actually more stable and more robust than the
conventional way Linux systems shut down. The major cost
is the 1-Meg or so of RAM needed the tmpfs for busybox. I think
the Linux distros should migrate to using busybox for the
shutdown process even when not running live.
Peace, James
_______________________________________________
busybox mailing list
busybox@busybox.net
http://lists.busybox.net/mailman/listinfo/busybox
