Perl/grep speed comparison

Sixtease has asked for the wisdom of the Perl Monks concerning the following question:

WTF is wrong with grep?

$ time grep '.' myfile
real    5m53.088s
[download]

$ time perl -ne '/./ and print' myfile
real    0m0.387s
[download]

Comment on Perl/grep speed comparison Select or Download Code

Replies are listed 'Best First'.
Re: Perl/grep speed comparison by tuxz0r (Pilgrim) on Nov 17, 2007 at 22:01 UTC
I don't see the kind of difference on my machine (G4 iBook running Mac OS X 10.5) as you do (I'm using a 30K file of all 'x's): `radar:~ datchley$ time grep "." myfile >/dev/null real 0m0.989s user 0m0.821s sys 0m0.078s radar:~ datchley$ time perl -ne '/./' myfile >/dev/null real 0m0.020s user 0m0.006s sys 0m0.013s` [download] How big is your file, what machine? --- `echo S 1 [ Y V U \| perl -ane 'print reverse map { $_ = chr(ord($_)-1) } @F;'` Warning: Any code posted by tuxz0r is untested, unless otherwise stated, and is used at your own risk.	[reply] [d/l]
Re: Perl/grep speed comparison by eserte (Deacon) on Nov 17, 2007 at 22:26 UTC
On my machine (an Athlon64 with amd64-freebsd) grep is always faster than perl. Using an 8MB test file: `$ time perl5.10.0 -ne '/./ and print' /boot/kernel/kernel > /dev/null 0.070u 0.015s 0:00.09 88.8% 1490+1246k 0+0io 0pf+0w $ time grep -a '.' /boot/kernel/kernel > /dev/null 0.026u 0.000s 0:00.03 66.6% 114+1056k 0+0io 0pf+0w` [download]	[reply] [d/l]
Re: Perl/grep speed comparison by Sixtease (Friar) on Nov 17, 2007 at 22:47 UTC
Guess I'll have to ask in the Gentoo forums then. But well... aliasing grep to pcregrep removed this slowness and I can use the regexes I love. :-)	[reply]