From owner-freebsd-questions@FreeBSD.ORG  Tue Jul 26 23:49:18 2005
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
X-Original-To: freebsd-questions@freebsd.org
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id A7AD816A41F
	for <freebsd-questions@freebsd.org>;
	Tue, 26 Jul 2005 23:49:18 +0000 (GMT)
	(envelope-from bob89@eng.ufl.edu)
Received: from scorpion.eng.ufl.edu (scorpion.eng.ufl.edu [128.227.116.10])
	by mx1.FreeBSD.org (Postfix) with SMTP id 1E05B43D48
	for <freebsd-questions@freebsd.org>;
	Tue, 26 Jul 2005 23:49:17 +0000 (GMT)
	(envelope-from bob89@eng.ufl.edu)
Received: (qmail 29936 invoked from network); 26 Jul 2005 23:49:17 -0000
Received: from scanner.engnet.ufl.edu (128.227.152.221)
	by scorpion.eng.ufl.edu with SMTP; 26 Jul 2005 23:49:17 -0000
From: Bob Johnson <bob89@eng.ufl.edu>
Organization: UF College of Engineering
To: freebsd-questions@freebsd.org
Date: Tue, 26 Jul 2005 19:49:15 -0400
User-Agent: KMail/1.7.2
MIME-Version: 1.0
Content-Type: text/plain;
  charset="us-ascii"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200507261949.16230.bob89@eng.ufl.edu>
Cc: matt@atopia.net
Subject: cat /dev/urandom
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 26 Jul 2005 23:49:18 -0000

 
Tue, Jul 26, 2005 at 6:32 PM Matt Juszczak <matt@atopia.net> 


> Hi all,
> 
> Quick question.
> 
> shell# cat /dev/urandom
> 
> can that executed as root cause any harm to the system?  What if a random
> sequence of `rm *` was generated... would it be executed?
> 

Not from a virtual terminal.  There may have been an old hardware "smart" 
terminals that would let you trick it into echoing stuff back through the 
keyboard buffer with the appropriate esc sequence, but emulators for those 
have such functions disabled by default these days, for the obvious reason.  
I'm willing to assume that includes whatever you are using for a terminal 
program.
 
> I tried that to fix my terminal and forgot it might cause damage as root,
> even if its just being cat'd to the screen.  I thought I saw some files
> fly by which would indicate an execution of `ls`....

Highly unlikely, unless you are actually using an old hardware terminal, then 
it is still pretty unlikely.

For example:


$ cat test.txt
This is a test file.
test
test
`ls -l /`
test


cat just types the characters out on the screen.  The `ls -l` didn't get 
executed.

> 
> Just curious....
> 

- Bob