Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!sun-barr!newstop!texsun!convex!news
From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.editors
Subject: Re: One user's editor wish list
Message-ID: <1991Mar20.203401.26237@convex.com>
Date: 20 Mar 91 20:34:01 GMT
References: <1991Feb22.134323.20410@scrumpy@.bnr.ca> <11032@dog.ee.lbl.gov>
Sender: news@convex.com (news access account)
Reply-To: tchrist@convex.COM (Tom Christiansen)
Organization: CONVEX Software Development, Richardson, TX
Lines: 33
Nntp-Posting-Host: pixel.convex.com


From the keyboard of torek@elf.ee.lbl.gov (Chris Torek):
:This is fixed in 10th Edition Unix.  It is just an accident of history.
:There *is* a reason for some difference, actually:  Editors must have
:a way of marking matches for substitutions, while pure matchers (grep)
:do not need this.

Untrue.  I use \references on the LHS of my substitutes, albeit
infrequently.  For example:

    prep '(\w+)\s+\1' *.ms

to find repeated words on the same line in a document.

--tom

ps: prep basically works out to be an alias like this:

    alias prep "perl -ne 'print if /$^/' \!:2-$"

accept I don't require the filenames.  In straight egrep, you would say:

    egrep '([a-zA-Z0-9_]+)[ ^I]+\1' *.ms

In grep it's more cumbersome still for lack of + operator.  Perl regexps
have some other nice properties, too, but I won't get into that here.

Anybody got a good way of doing "word-boundaries" in egrep?  In grep
you can use -w, but only gnu's egrep takes it.  I use \b in perl, \<
in vi, but egrep is a pain for this.  Well, that's what the prep alias
is for I guess.

--tom