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From: subbarao@phoenix.Princeton.EDU (Kartik Subbarao)
Newsgroups: comp.unix.questions
Subject: Re: unopenable tty
Message-ID: <2678@idunno.Princeton.EDU>
Date: 20 Sep 90 21:00:08 GMT
References: <6429@castle.ed.ac.uk>
Sender: news@idunno.Princeton.EDU
Lines: 17

In article <6429@castle.ed.ac.uk> expc55@castle.ed.ac.uk (Andrew Myles) writes:
>ioctl(1,TIOCEXCL);		/* no more opens - when I use this I find
>				   that mail demons cannot tell me of new
>				   mail, sysops cannot wall etc... :-) */
>

This is not the case! "biff", "talk" and "wall" seem to work fine for me
even with the tty - exclusive on mode. The reason talk works is because the
talk daemon is a root process, and "wall" is a setuid root (or root run)
program. As to "mail", it is another thing which works. Root can have his
way regardless of what you do.

I ran a program like this for quite a while (still do) to stop direct writes
on my tty with cat and friends, but still allow talk messages.
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