Hide

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again.

Delete that bloated snippets file you've been using and share your personal repository with the world. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

If you have a new feature suggestion or find a bug, please get in touch via http://commandlinefu.uservoice.com/

Get involved!

You can sign-in using OpenID credentials, or register a traditional username and password.

OpenID
or
Sign in Register

First-time OpenID users will be automatically assigned a username which can be changed after signing in.

Hide

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for:

Hide

News

2011-03-12 - Confoo 2011 presentation
Slides are available from the commandlinefu presentation at Confoo 2011: http://presentations.codeinthehole.com/confoo2011/
2011-01-04 - Moderation now required for new commands
To try and put and end to the spamming, new commands require moderation before they will appear on the site.
2010-12-27 - Apologies for not banning the trolls sooner
Have been away from the interwebs over Christmas. Will be more vigilant henceforth.
2010-09-24 - OAuth and pagination problems fixed
Apologies for the delay in getting Twitter's OAuth supported. Annoying pagination gremlin also fixed.
Hide

Tags

Hide

Functions

Hide

Credits

Site by David Winterbottom (user root).

To print a specific line from a file

Terminal - To print a specific line from a file
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 :)

Add to favourites | Report as malicious

Alternatives

There are 3 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>
Comments (0) | Add to favourites | Report as malicious
tail -n +<N> <file> | head -n 1
2011-09-30 08:30:30
User: qweqq
Functions: head tail
Tags: sed awk tail grep printing print line number
-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.

Show sample output | Comments (2) | Add to favourites | Report as malicious

Know a better way?

If you can do better, submit your command here.

What others think

MUCH easier to write:

awk 'NR ==3' file
Comment by arcege 191 weeks and 2 days ago

The head/tail method doesn't deserve the downvotes, it's the fastest of the three methods. Try it on a large log file and see.

Comment by plasticboy 191 weeks ago

Your point of view

You must be signed in to comment.

Related sites and podcasts