www.nico.schottelius.org/blog/about-init-dependencies.mdwn

[[!meta title="About init dependencies"]]


As i started to hack on [cinit](http://unix.schottelius.org/cinit/) again,
I tried to get it running on Debian in a VM.

I took the old configuration from my last computer and tried to boot
with cinit, which failed, because the udev stuff changed.

So I added a udev service, which uses /etc/init.d/udev for switching on.

After booting the VM, I recognized, that the service
***mount/proc*** (which mounts /proc...) fails. Mount claims that
/proc it is already mounted!

This is caused by the udev script, which contains:

    237    [ -d /proc/1 ] || mount -n /proc

Besides the problematic of using a sys-v-init script with an
intelligent init system, it's interesting to see, **why**
this happens:

The service mount/root needs the device files in /dev
to be able to run mount/root/fsck (the filesystem check).

Thus mount/root requires the service udev to be started before.

The service mount/proc needs the root filesystems writable,
to write into /etc/mtab and thus needs mount/root.

This also demonstrates the problematic of the historical grown
init scripts, which do way more than one job and their lack of
real dependencies.

[[!tag unix]]