UMASK: need help explaining it

[Andy Clews]

I'm writing a guide to UN*X for our Computing Service, and the ugly
subject of umask has surfaced.  Our system is DYNIX 3.0.17 (based mostly
on 4.2BSD) and the umask is the old-style one wherein you have to
specify default protection codes as a 1's complement number.  Not only
does this scare the hell out of novices, it is also giving me a sore
brain trying to work out the simplest way of explaining how to use it.

Has anyone out there ever succeeded in explaining the old umask to
novices and had them go away happy? If so, I would be eternally grateful
if you would be willing to share your wisdom with me.  I'll even give
donors an acknowledgement in my guide ("big deal" I hear you cry :-)

Marks will be awarded for conciseness and the less buzzwords and
computerese the better!

Please note: only the "umask 022" style is acceptable. Those lucky
people with the "umask u=rw" version can go and be smug elsewhere!   ;-)

Feel free to email me. I will probably summarise if any umaskophobes out
there would like to benefit from this discussion.

Thanks for listening.

-- 
Andy Clews, Computing Service, Univ. of Sussex, Brighton BN1 9QN, England
JANET: andy at syma.sussex.ac.uk   BITNET: andy%syma.sussex.ac.uk at uk.ac