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Fast grepping (avoiding UTF overhead)

Terminal - Fast grepping (avoiding UTF overhead)
export LANG=C; grep string longBigFile.log
2009-07-14 12:48:02
User: ioggstream
Functions: export grep
0
Fast grepping (avoiding UTF overhead)

greps using only ascii, skipping the overhead of matching UTF chars.

Some stats:

$ export LANG=C; time grep -c Quit /var/log/mysqld.log

7432

real 0m0.191s

user 0m0.112s

sys 0m0.079s

$ export LANG=en_US.UTF-8; time grep -c Quit /var/log/mysqld.log

7432

real 0m13.462s

user 0m9.485s

sys 0m3.977s

Try strace-ing grep with and without LANG=C

Alternatives

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Terminal - Alternatives

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What others think

Tried, saw no effect.

Comment by penpen 249 weeks and 1 day ago

No difference here either in Fedora 11, or Ubuntu 9.04.

Comment by flatcap 249 weeks and 1 day ago

Maybe you're still in LANG=C ;)

Try setting another LANG and grep.

Comment by ioggstream 249 weeks ago

I tried setting LANG to both values and after the cache gets hot, I see no difference under ubuntu.

Comment by bwoodacre 249 weeks ago

test made on RHEL. The same applies to many *nixes

see

https://bugzilla.redhat.com/show_bug.cgi?id=499220

it seems fixed on ubuntu 9.04

Comment by ioggstream 248 weeks and 6 days ago

you dont have to actually do the export. If you remove the export and the semi-colon around the LANG=C the LANG envirnoment variable will become C for as long as the grep command runs.

echo $LANG

gives en_US.utf8

LANG=C grep 'foo' /var/log/whatever.log.0

runs in a quicker mode on some distros

echo $LANG

still gives en_US.utf8;

Comment by coffeeaddict_nl 245 weeks and 1 day ago

Your point of view

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