From owner-freebsd-questions@FreeBSD.ORG Sat Jan 25 03:49:35 2014 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 321B4470 for ; Sat, 25 Jan 2014 03:49:35 +0000 (UTC) Received: from cdptpa-oedge-vip.email.rr.com (cdptpa-outbound-snat.email.rr.com [107.14.166.225]) by mx1.freebsd.org (Postfix) with ESMTP id D822A183D for ; Sat, 25 Jan 2014 03:49:34 +0000 (UTC) Received: from [76.183.65.74] ([76.183.65.74:65523] helo=[192.168.1.32]) by cdptpa-oedge02 (envelope-from ) (ecelerity 3.5.0.35861 r(Momo-dev:tip)) with ESMTP id 79/06-11837-B4433E25; Sat, 25 Jan 2014 03:49:33 +0000 Date: Fri, 24 Jan 2014 21:49:31 -0600 From: Paul Schmehl To: Warren Block , 'Devin Teske' Subject: RE: awk programming question Message-ID: <834811727E040B4079BD1CB4@Pauls-MacBook-Pro.local> In-Reply-To: References: <20140123185604.4cbd7611@gumby.homeunix.com> <04a201cf1878$8ebce540$ac36afc0$@FreeBSD.org> <04aa01cf187e$cfcf9ef0$6f6edcd0$@FreeBSD.org> <04d201cf1895$20956890$61c039b0$@FreeBSD.org> <050a01cf1929$051c0670$0f541350$@FreeBSD.org> X-Mailer: Mulberry/4.0.8 (Mac OS X) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline X-RR-Connecting-IP: 107.14.168.130:25 X-Cloudmark-Score: 0 Cc: 'RW' , freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list Reply-To: Paul Schmehl List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 25 Jan 2014 03:49:35 -0000 --On January 24, 2014 10:34:47 AM -0700 Warren Block wrote: > On Fri, 24 Jan 2014, dteske@FreeBSD.org wrote: > >>>> I'm not entirely sure how I feel about that -- in terms of >>>> readability, I'm not sure if the following is more readable: >>>> >>>> /(a[^z]*z)/ >>> >>> Wait till you see the other PCRE stuff. There are lots of things >>> that really make it much more powerful. perlre(1) covers it all, >>> sketchily and not really in order. >>> >>> I've said elsewhere, and will repeat again: "Mastering Regular >>> Expressions" by Jeffrey E. F. Friedl (the owl book) is amazing. My >>> first edition (1997) does not have some of the newer Perl stuff, but >>> it's now up to a third edition: >>> >>> http://shop.oreilly.com/product/9780596528126.do >> >> Does it cover "back references" ? Definitely one of the more powerful >> but esoteric regular expressions (e.g., you want to match a string >> that starts with a quote and has a matching terminating quote, but not >> match a string that has a quote without matching termination). > > It does cover backreferences, in the sense of egrep: > \<[A-Za-z]+) +\1\> > > That will find a word followed by one or more spaces and the same word > again. > >> If-so, I'm totally buying that book. > > Buy it. I've never seen another book that treats such a complex subject > with such clarity and readability. I can't possibly thank you gentlemen enough for this wonderful discussion of awk and perl and regex. Thank you for sharing your insights and knowledge. Paul Schmehl, Senior Infosec Analyst As if it wasn't already obvious, my opinions are my own and not those of my employer. ******************************************* "It is as useless to argue with those who have renounced the use of reason as to administer medication to the dead." Thomas Jefferson "There are some ideas so wrong that only a very intelligent person could believe in them." George Orwell