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Path: utzoo!watmath!clyde!burl!ulysses!smb
From: smb@ulysses.UUCP (Steven Bellovin)
Newsgroups: net.mail
Subject: Re: parsing host1!user@host2 - a new idea
Message-ID: <1034@ulysses.UUCP>
Date: Tue, 23-Oct-84 10:43:47 EDT
Article-I.D.: ulysses.1034
Posted: Tue Oct 23 10:43:47 1984
Date-Received: Wed, 24-Oct-84 03:59:53 EDT
References: <339@haring.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 27

Using parentheses will badly break lots of existing software, for several
reasons.

	(a) rfc822 treats parenthesized stuff as comment.

	(b) lots of mailers use 'system()' or equivalent to invoke the
	next mailer down the forwarding chain; think of what unquoted
	parentheses do when the shell gets hold of them.  (You wouldn't
	believe what our shell does, but even /bin/sh won't like them.)

	(c) Parentheses are already used as an (undocumented) part of the
	uux protocol...  That is, if you say

		uux foo!command a!b

	your uux will try to ship file 'b' from machine 'a' to 'foo' before
	executing 'command'.  It doesn't matter the command is really

		uux foo!rmail host!user

	uux has no way of knowing.  To get around this, mailers generate

		uux foo!rmail \(host!user\)

	to pass to the shell; the parentheses in turn tell uux that the
	funny string with a '!' is to be passed on literally, and is not
	a file transfer request.