Undocumented features

[rcd at opus.UUCP]

Guy Harris, commenting on another netter's discovery that a needed feature
actually exists but is undocumented:
>Yup.  Welcome to the wonderful world of UNIX; a treasure hunt each day.
>The annoying thing is that some of the stuff are real treasures, but the
>authors have seen fit to bury them deeply...

But look things over carefully before you use them.  I remember chasing
fopen(3) in V7 - I wanted to be able to open a file for both reading and
writing, so I set out to add code to do this.  Turned out that the code was
already there - in addition to the documented "r", "w", and "a" options,
you could add "+" to get read/write, as in "w+".  However, it didn't
work...so was it undocumented because whoever wrote it not only blew it but
didn't document it, or (more likely) because it wasn't done at the time the
system was shipped?  In any case, I had only myself to blame for using an
undocumented feature.
-- 
...Stop to smell the flowers.				Dick Dunn
{hao,ucbvax,allegra}!nbires!rcd				(303) 444-5710 x3086