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May 19, 2015 - A Look At The New Commandlinefu
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Efficiently print a line deep in a huge log file

Terminal - Efficiently print a line deep in a huge log file
sed '1000000!d;q' < massive-log-file.log
2009-01-26 11:50:00
User: root
Functions: sed
Efficiently print a line deep in a huge log file

Sed stops parsing at the match and so is much more effecient than piping head into tail or similar. Grab a line range using

sed '999995,1000005!d' < my_massive_file


There is 1 alternative - vote for the best!

Terminal - Alternatives

Know a better way?

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What others think

I prefer:

sed -n '1000000p' massive-log-file.log
Comment by penthief 368 weeks and 4 days ago

Have you done tests? In my examples (line 10 mio from a 19 mio lines file) head|tail was faster. sed was only slightly faster if you write:

head -n 10000001 | tail -n 2

0.9 sec utime, 2 sec clock time

sed -n '10000000,10000001p'

1.7 sec utime, 2.2 sec clock time

sed -n '10000000,10000001p;10000002q'

0.9 sec utime, 1.2 sec clock time

Otherwise sed will parse until the end, what head|tail doesn't.

Overall the time differences seem irrelevant. It's more a question of beauty. :-)

Comment by weidenrinde 26 weeks and 5 days ago

Your point of view

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