jtc@van-bc.wimsey.bc.ca (J.T. Conklin) (10/08/90)
In article <3790@awdprime.UUCP> tif@doorstop.austin.ibm.com (Paul Chamberlain) writes: >Fgrep means Fixed, egrep means Exponential (like in Exponentially faster)! >If you care one tiny bit about the speed you'll only use fgrep when you >have to. Now can we stop discussing the fastest way to use fgrep? > >This lesson is a review for those that didn't believe it the first time. As has been mentioned before, it depends on your implementation: not all fgreps are slow. I compared the speeds of GNU fgrep, GNU egrep, SCO XENIX fgrep, and SCO XENIX egrep by searching for the word "dictionary" in a file containing fourty-two copies of /usr/dict/words. Execution speeds were as follows: GNU fgrep 10s GNU egrep 11s SCO egrep 16s SCO fgrep 59s --jtc -- J.T. Conklin UniFax Communications Inc. ...!{uunet,ubc-cs}!van-bc!jtc, jtc@wimsey.bc.ca
tif@doorstop.austin.ibm.com (Paul Chamberlain) (10/09/90)
In article <2440@van-bc.wimsey.bc.ca> jtc@van-bc.wimsey.bc.ca (J.T. Conklin) writes: >In article <3790@awdprime.UUCP> tif@doorstop.austin.ibm.com (Paul Chamberlain) writes: >>Fgrep means Fixed, egrep means Exponential (like in Exponentially faster)! >As has been mentioned before, it depends on your implementation: not >all fgreps are slow. I confess, my statement was based just on SCO XENIX although I have been led to believe than SysV also acted this way. I just tried two AIX's. AIX V2.2.1 fgrep is only slightly slower than egrep, and AIX V3.1 fgrep is slightly faster than egrep! Paul Chamberlain | I do NOT represent IBM. tif@doorstop, sc30661 at ausvm6 512/838-7008 | ...!cs.utexas.edu!ibmaus!auschs!doorstop.austin.ibm.com!tif
greg@tcnz2.tcnz.co.nz (Greg Calkin) (10/10/90)
In article jtc@van-bc.wimsey.bc.ca (J.T. Conklin) writes: >In article tif@doorstop.austin.ibm.com (Paul Chamberlain) writes: >>Fgrep means Fixed, egrep means Exponential (like in Exponentially faster)! >>If you care one tiny bit about the speed you'll only use fgrep when you >>have to. Now can we stop discussing the fastest way to use fgrep? >> >>This lesson is a review for those that didn't believe it the first time. > >As has been mentioned before, it depends on your implementation: not >all fgreps are slow. Quite correct - in the NCR tower documentation, you get An eqrep pattern is a full regular expression; egrep uses a fast deterministic algorithm that sometimes needs exponential space. Fgrep patterns are fixed strings; fgrep is fast and compact. My testing in the past has born this out - for simple tasks, fgrep is much quicker. So, this lesson is a review for those that believe that all Unixes are the same. RTFM and experiment. -- Greg Calkin, Systems Engineer {include "sexual_hard_sell"} (greg@tcnz.co.nz) Thomas Cook N.Z. Limited, PO Box 24, Auckland CPO, New Zealand, Ph (09)-793920 Disclaimer : Would you buy a used car from someone with these opinions ?