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From: dan%sri-tsc@sri-unix.UUCP
Newsgroups: net.unix-wizards
Subject: Re: ed
Message-ID: <12083@sri-arpa.UUCP>
Date: Tue, 27-Sep-83 12:14:00 EDT
Article-I.D.: sri-arpa.12083
Posted: Tue Sep 27 12:14:00 1983
Date-Received: Fri, 30-Sep-83 02:02:37 EDT
Lines: 20

The Air Force Data Services Center modified the ed substitute command
to do just what you want (substitute on the n-th instance of a RE
in a line).  In the example you cited, the command would be:

	s5/i/i++/p

to substitute the fifth instance of "i" on the line to "i++".  If you put
a "g" on the end of the line it would substitute the 5th through the
last occurance on the line (which is a noop in this example).

They made lots of other nifty modifications to ed -- the best of which was
to allow you to just say "/string" when searching for "string" and save
the keystrokes of "/p".  Since 80% of what I do in ed is searching, that
turns out to be a big win.

I believe a copy of their code is on some of the earlier USENIX tapes
(three to five years ago).  It's v6 based, but would be worth converting
if you are a big ed fan.

	-Dan Chernikoff (dan@sri-tsc)