From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from relay1.UU.NET ([137.39.1.5]) by archone.tamu.edu with SMTP id <18921>; Fri, 31 Jan 1992 15:12:54 -0600
Received: from uunet.uu.net (via LOCALHOST.UU.NET) by relay1.UU.NET with SMTP 
	(5.61/UUNET-internet-primary) id AA04225; Fri, 31 Jan 92 16:12:37 -0500
Received: from srg.UUCP by uunet.uu.net with UUCP/RMAIL
	(queueing-rmail) id 161111.10046; Fri, 31 Jan 1992 16:11:11 EST
Received: from ceres.srg.af.mil by srg.srg.af.mil
	id aa28925; Fri, 31 Jan 92 16:01:14 EST
From: culliton@srg.af.mil (Tom Culliton x2278)
X-Mailer: SCO System V Mail (version 3.2)
To: rc@archone.tamu.edu
Subject: Match operator puzzlement
Date: Fri, 31 Jan 1992 15:01:15 -0600
Message-Id: <9201311601.aa02527@ceres.srg.af.mil>

Reply-To: srg!culliton@uunet.uu.net

OK maybe it's just 'cuz it's Friday but my poor brain refuses to come
up with a good answer to this one.  While writing some fairly large and
complex rc scripts I had a requirement to match something against a
list of patterns specified at the command line and figured it'd be easy
give rc's ~ match operator.

The first attempt was something like this:

	patterns=`{echo $1}	# go from '*.o *.a' to (*.o *.a)

	# lots of stuffto generate a list on file names....

	for (i in $list) {
		if (~ $i $patterns) {
			dealwith $i
		} else {
			handle $i
		}
	}

Which didn't work as planned for semi-obvious reasons involving
re-scanning.  This didn't distress me too much because I mostly
understood why after a bit of thought.  The next most obvious thing to
try was somthing like this

	patterns=$1	# we don't care if it's a list for this

	# lots of stuff to generate a list on file names....

	for (i in $list) {
		if (eval ~ $i $patterns) {	# etc...

OOPS! I encountered a file name with a $ in it so make that

		if (eval ~ '$i' $patterns) { 	# etc...

But what about patterns with $ and so forth in them?  If we make
$patterns a list again and say '$patterns' to protect against that, we
get literal matching.  I haven't been able to find a way out of the
swamp here any words of wisdom would be appreciated.

Thanks for listening.

Tom