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From: smb@ulysses.UUCP (Steven Bellovin)
Newsgroups: net.bugs.4bsd,net.unix-wizards,net.bugs.usg
Subject: Re: Re: Bug in isatty (all systems!)
Message-ID: <1017@ulysses.UUCP>
Date: Tue, 23-Jul-85 13:25:50 EDT
Article-I.D.: ulysses.1017
Posted: Tue Jul 23 13:25:50 1985
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> For those keepers of the true faith who savaged my coding practices,
> this is exactly my point.  I designed a large software system around
> the assumption that errno was always valid and not set as a side-effect.
> It took me 6 months (admittedly, I wasn't looking hard) to figure out
> why I was always getting "not a typewriter" (because my open routine 
> was setting a struct bit to indicate tty/non-tty for every file).
> 
> My reason for posting this was to call attention to an error in the
> documentation.  All the manuals I've seen are in error, because this
> is a known, established, important "SPECIAL CONSIDERATION".

My 4.2bsd manual describes this in the INTRO(2) section, right before the
list of errno values.  Just where would you prefer that it be mentioned?
RTFM!