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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
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


real 0m0.191s

user 0m0.112s

sys 0m0.079s

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


real 0m13.462s

user 0m9.485s

sys 0m3.977s

Try strace-ing grep with and without LANG=C


There are 8 alternatives - vote for the best!

Terminal - Alternatives

Know a better way?

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What others think

Tried, saw no effect.

Comment by penpen 458 weeks ago

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

Comment by flatcap 458 weeks ago

Maybe you're still in LANG=C ;)

Try setting another LANG and grep.

Comment by ioggstream 458 weeks ago

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

Comment by bwoodacre 457 weeks and 6 days ago

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



it seems fixed on ubuntu 9.04

Comment by ioggstream 457 weeks and 5 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 454 weeks ago

Your point of view

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