Date: Fri, 24 Jan 2014 10:34:47 -0700 (MST) From: Warren Block <wblock@wonkity.com> To: "'Devin Teske'" <dteske@FreeBSD.org> Cc: 'RW' <rwmaillists@googlemail.com>, freebsd-questions@freebsd.org Subject: RE: awk programming question Message-ID: <alpine.BSF.2.00.1401241029230.89161@wonkity.com> In-Reply-To: <050a01cf1929$051c0670$0f541350$@FreeBSD.org> References: <F01EB9CE742DEB17DB6B51C7@localhost> <alpine.BSF.2.00.1401230900270.76961@wonkity.com> <20140123185604.4cbd7611@gumby.homeunix.com> <04a201cf1878$8ebce540$ac36afc0$@FreeBSD.org> <alpine.BSF.2.00.1401231346520.80613@wonkity.com> <04aa01cf187e$cfcf9ef0$6f6edcd0$@FreeBSD.org> <alpine.BSF.2.00.1401231537260.80613@wonkity.com> <04d201cf1895$20956890$61c039b0$@FreeBSD.org> <alpine.BSF.2.00.1401231904410.82598@wonkity.com> <050a01cf1929$051c0670$0f541350$@FreeBSD.org>
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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.
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