Path: utzoo!attcan!uunet!husc6!mailrus!cornell!uw-beaver!teknowledge-vaxc!sri-unix!quintus!ok
From: ok@quintus.uucp (Richard A. O'Keefe)
Newsgroups: comp.unix.wizards
Subject: Re: End-of-file character (was script > mumble)
Message-ID: <523@quintus.UUCP>
Date: 12 Oct 88 02:18:34 GMT
References: <4975@saturn.ucsc.edu> <503@quintus.UUCP> <1503@fireball.cs.vu.nl>
Sender: news@quintus.UUCP
Reply-To: ok@quintus.UUCP (Richard A. O'Keefe)
Organization: Quintus Computer Systems, Inc.
Lines: 36

In article <1503@fireball.cs.vu.nl> maart@cs.vu.nl (Maarten Litmaath) writes:
>In article <503@quintus.UUCP> ok@quintus.UUCP (Richard A. O'Keefe) writes:
>\... here's some source code:
>[C source deleted]
>
>People, what happened to good old shell script programming?

Well, it's very simple.  I wanted my __C__ programs to be able to remind
their users what to type to get an end-of-file.  So I wrote a C function.
The main() in that file was enclosed in #ifdef TEST, remember!
(I have received some mail pointing out problems, esp. with System V.)

>BSD:
>sh -c 'stty all 2> /tmp/stty.$$; set `tail -1 /tmp/stty.$$`;
>	shift; shift; echo $9; /bin/rm /tmp/stty.$$'

It is very easy to break this (took me 2 minutes),
and in any case on the system I am using I get the answer "^Z/^[",
which is wrong (it should be "^Z").

>SysV:
>sh -c 'stty -a | sed -e "s/.*eof = \([^;]*\).*/\1/" -e q'

It is also easy to break this (took me 5 minutes; I don't know SysV well).

Forking off three programs (sh, stty, rm or sed) would be a very odd thing
to do in a C program when you can get the same information with a few
system calls.

While we're on the subject, I have read the SVID termio(ba_env) section
several times, and cannot tell whether there is any general way of
disabling individual elements of c_cc[] or not.  Setting c_cc[VEOL] to
ASCII NUL appears to disable that feature.  In DYNIX V3.0.12 NFS,
SunOS 3.2, and UNIX System V/386 Release 3.0, setting c_cc[VKILL] to
ASCII NUL merely makes ^@ the kill character.  Does anyone know which
elements of c_cc[] can be suppressed and which can't?