unix documentation

[utzoo!decvax!ucbvax!mhtsa!ihnss!cbosg!mark]

You CAN'T in general assume people can go look at the source to
figure out what an error means.  Aside from the obvious fact that
there are lots of users who don't speak C, recall that to get Unix
a (non-Bell) site has to sign in blood a promise not to give out the
sources to anyone.  Many sites (especially University Computer Centers,
who don't trust their users) protect /usr/src.  (I know of one comp
ctr at an unnamed major university in Berkeley that doesn't even make
df suid because "It's none of your business if the disks are full".
Since they also overbook disk quotas, which they have, this is a fun
place to try to get any work done.)  An even worse case is typified
by Onyx, Microsoft, and other turnkey Unix system sources who don't
let you have ANY sources.  This is how a small business can afford
to buy Unix - to not pay for a full source license.  These poor guys
can't go look at the source, and I can't tell you how many times I've
wished I could in order to pinpoint some bug.