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From: rang@cpsin3.cps.msu.edu (Anton Rang)
Newsgroups: comp.unix.wizards
Subject: Re: Priority messages in Unix
Message-ID: <2522@cps3xx.UUCP>
Date: 14 Apr 89 17:27:59 GMT
References: <1857@wpi.wpi.edu> <538@lakesys.UUCP> <539@lakesys.UUCP>
Sender: usenet@cps3xx.UUCP
Reply-To: rang@cpswh.cps.msu.edu (Anton Rang)
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Organization: Michigan State University, Computer Science Dept.
Lines: 20
In-reply-to: chad@lakesys.UUCP's message of 14 Apr 89 03:06:31 GMT

In article <539@lakesys.UUCP> chad@lakesys.UUCP (Chad Gibbons) writes:
>  On most BSD-derivative systems no user other than the owner has
>access to your tty, nor can you modify your own.  Talk requests and such
>are done through a system of daemon processes which control user access
>to each other.  This was done in order to remove the ever frustrating
>moment when someone does a "cat</etc/hosts>/dev/ttyxx&" to your terminal.
>-- 
>D. Chadwick Gibbons, chad@lakesys.lakesys.com, ...!uunet!marque!lakesys!chad

  Unfortunately, at least in SunOS 3.4 (4.2-BSD derived), this isn't
quite true.  Yes, talk requests etc. are done through a system of
daemons.  But you don't get talk requests etc. unless you execute
'mesg y', which turns on world write access to your /dev/tty, which
allows "cp /etc/hosts /dev/ttypxx" (or your favorite command...I
always liked echoing a power-on reset sequence :-)....

+---------------------------+------------------------+----------------------+
| Anton Rang (grad student) | "VMS Forever!"         | "Do worry...be SAD!" |
| Michigan State University | rang@cpswh.cps.msu.edu |                      |
+---------------------------+------------------------+----------------------+