[TUHS] Short history of 'grep'

Larry McVoy lm at mcvoy.com
Sat Mar 5 11:54:13 AEST 2016


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 


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