Story time:
In the old days of original unices, before sysadmins had a clue, there
were some that said things like
"/dev/null is an empty file; let's delete it"
They'd then remove it, and it would be recreated as an ordinary file.
Many many processes would then write to it, and it would eventually
fill the entire root partition with stuff that should have been
consigned to a black hole.
Same goes for /dev/zero. They'd remove it, and find that half their
apps didn't work. Basically, /dev/zero is often used for initialising
memory to a safe value; there used to be cracks where a program would
get some memory, then trawl it for passwords. Nowadays, memory is
usually zeroed out before it's given to an app, usually by reading from
/dev/zero. So without it, apps can't actually intialise...

Next hint: MKNOD is a program used to create device files. If it's not
statically linked, then your system is, most of the time, unable to
create device files. Great for comedy value, but if it's not working
then you have to do a complete reinstall.

Gary (-;