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To print a specific line from a file

Terminal - To print a specific line from a file
tail -n +<N> <file> | head -n 1
2011-09-30 08:30:30
User: qweqq
Functions: head tail
-5
Up
Down
To print a specific line from a file

Tail is much faster than sed, awk because it doesn't check for regular expressions.

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Alternatives

There are 7 alternatives - vote for the best!

Terminal - Alternatives
sed -n 5p <file>
2009-10-15 11:00:48
User: Waldirio
Functions: sed
35
Up
Down
To print a specific line from a file

You can get one specific line during any procedure. Very interesting to be used when you know what line you want.

Show sample output | Comments (2) | Add to favourites | Report as malicious
awk 'FNR==5' <file>
2009-10-20 22:52:41
User: dennisw
Functions: awk
0
Up
Down
To print a specific line from a file

Just one character longer than the sed version ('FNR==5' versus -n 5p). On my system, without using "exit" or "q", the awk version is over four times faster on a ~900K file using the following timing comparison:

testfile="testfile"; for cmd in "awk 'FNR==20'" "sed -n '20p'"; do echo; echo $cmd; eval "$cmd $testfile"; for i in {1..3}; do time for j in {1..100}; do eval "$cmd $testfile" >/dev/null; done; done; done

Adding "exit" or "q" made the difference between awk and sed negligible and produced a four-fold improvement over the awk timing without the "exit".

For long files, an exit can speed things up:

awk 'FNR==5{print;exit}' <file>
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awk '{if (NR == 3) print}' <file>
2009-10-19 15:58:09
User: yooreck
Functions: awk
-5
Up
Down
To print a specific line from a file

I don't know if it's better but works fine :)

Comments (2) | Add to favourites | Report as malicious

Know a better way?

If you can do better, submit your command here.

What others think

What does "much faster mean"?

I made a test with 100000 lines file - difference is ~1ms

Comment by zolden 85 weeks ago
su root wc -l file

394955588 file

sync && echo 1 > /proc/sys/vm/drop_caches time sed -n -e '390955588 p' file

/075c6142-c331-4e78-8e5a-4b7b5520edc1.html

real 8m25.225s

user 1m15.680s

sys 0m10.820s

sync && echo 1 > /proc/sys/vm/drop_caches time tail -n +390955588 file | head -n 1

/075c6142-c331-4e78-8e5a-4b7b5520edc1.html

real 2m34.209s

user 0m13.160s

sys 0m10.150s

With "awk 'FNR=='390955588'" a wrong line was outputted and it took ~11m. The file i tested the posted command with is 21GB.

100k lines is a small file. It is about maybe 10MB in which case the difference is hard to see.

Test machine specs:

Intel Core i7 920

2x 1TB HDDs in Software Raid 1

Comment by qweqq 81 weeks and 6 days ago

Your point of view

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