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From: stevesu@copper.UUCP
Newsgroups: comp.unix.wizards
Subject: Re: reading from terminal
Message-ID: <1123@copper.TEK.COM>
Date: Sat, 13-Jun-87 17:57:17 EDT
Article-I.D.: copper.1123
Posted: Sat Jun 13 17:57:17 1987
Date-Received: Sun, 14-Jun-87 18:37:21 EDT
References: <7749@brl-adm.ARPA>
Organization: Tektronix Inc., Beaverton, Or.
Lines: 29

In article <7749@brl-adm.ARPA>, jfjr@mitre-bedford.arpa (Freedman) writes:
> I need to read a character from the terminal without stopping a
> program.  I have done this successfully and simply on VMS using qio
> with the proper flag but I am having problems doing it on Unix.
> 
>   I really must say that Unix documentation compared to
> VMS doesn't measure up...

As several people have already mentioned, ioctl(FIONREAD) and
select() are fairly general and somewhat portable solutions under
Unix.  You might have mentioned the specific qio options you used--
some of us Unix wizards have ventured off into VMS and lived to
tell about it.  If you were doing true asynchronous I/O, by using
qio (as opposed to qiow) and specifying an AST completion routine,
you may find some equivalents on Unix; look at fcntl(2), if you
have it, specifically the FNDELAY and FASYNC options.  Beware
that these facilities are newer, buggier, less portable, and
harder to use than the more mature parts of Unix.

I won't defend Unix documentation, but I'll throw in a potshot at
VMS--I'd find its documentation a lot easier to use if it had an
index that was at all usable.  I have _n_e_v_e_r in my entire life
looked up a topic in a VMS index and found what I was looking
for, even when I knew that I'd read exactly what I was looking
for once before.  (Please, no Unix vs. VMS holy wars in response
to this.)

                                           Steve Summit
                                           stevesu@copper.tek.com