From mboxrd@z Thu Jan 1 00:00:00 1970 From: lm@mcvoy.com (Larry McVoy) Date: Fri, 4 Mar 2016 17:54:13 -0800 Subject: [TUHS] Short history of 'grep' In-Reply-To: References: <201601311701.u0VH12It027916@coolidge.cs.Dartmouth.EDU> Message-ID: <20160305015413.GI21241@mcvoy.com> You guys really need to go look at gnu grep. It blows away unix grep in terms of performance. http://lists.freebsd.org/pipermail/freebsd-current/2010-August/019310.html The guy writing that post did gnu grep. He was also a guy at Intel that did all sorts of magic. I've got a guy working for me, crazy smart guy, his job at Intel was taking Haertel's code and dumbing it down so they had some chance of supporting it. Read that post, Mike is one smart dude. On Sat, Mar 05, 2016 at 12:48:19PM +1100, Dave Horsfall wrote: > On Sun, 31 Jan 2016, Doug McIlroy wrote: > > [...] > > > That's the short story. In real life egrep overcomes the exponential by > > lazily constructing the machine--not generating a state until it is > > encountered in the parse, so no more than n states get constructed. It's > > a complex program, though, for the already fancy preprocessing must be > > interleaved with the parsing. > > Many thanks; I think I understand a little better now... It's been many > years since I majored in Computer Science :-) > > -- > Dave Horsfall DTM (VK2KFU) "Those who don't understand security will suffer." -- --- Larry McVoy lm at mcvoy.com http://www.mcvoy.com/lm