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From: brian@bucc2.UUCP
Newsgroups: comp.unix.questions
Subject: Re: Three-way write
Message-ID: <15100002@bucc2>
Date: Tue, 27-Oct-87 13:28:00 EST
Article-I.D.: bucc2.15100002
Posted: Tue Oct 27 13:28:00 1987
Date-Received: Sun, 1-Nov-87 03:14:58 EST
References: <273@ddsw1.UUCP>
Lines: 31
Nf-ID: #R:ddsw1.UUCP:273:bucc2:15100002:000:1395
Nf-From: bucc2.UUCP!brian    Oct 27 12:28:00 1987


> /* Written  5:06 pm  Oct 21, 1987 by sfsup.UUCP!mpl in bucc2:comp.unix.ques */
> Has anyone ever considered writing a "write" program that writes to ttys?
> Amazingly enough, this is how the two way "write" program does it, and guess
> what?  It's portable!  I know there are certain drawbacks, like each user
					  ^^^^^^^^^^^^^^^^^
> must know all the other users in the conversation, but guess what?  It's
> portable.
> 
> Sorry to sound facetious, but I'm sick of porting little programs like "this
> does a cat backwards, and uses semaphores."  Peace.
> 
> Mike Lindner
> attunix!mpl
> /* End of text from bucc2:comp.unix.ques */

  You sure are right there are certain drawbacks! In order to make the
wonderful, standard, portable write command work everyone on the system has
permission to write to your tty. Consider the implications of that. Novices
troublemakers can have fun by doing things like cat a.out > /dev/tty101, and
worse. People who know what they are doing can send wonderful control sequences
to your terminal. Wonderful control sequences that will make the system think
_you_ typed whatever _they_ want it to think. Like rm -r *


...............................................................................

  I heard it on the grep-vine...
						       { bucs1!brian
  Brian Michael Wendt	 {uiucdcs,cepu,ihnp4}!bradley! {       brian
 						       { bucc2!brian