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.

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

Commands using cat from sorted by
Terminal - Commands using cat - 417 results
sudo aptitude -y install iasl && sudo cat /sys/firmware/acpi/tables/DSDT > dsdt.dat && iasl -d dsdt.dat
2009-02-15 23:13:50
User: brettalton
Functions: cat install sudo
-1

In July 2008, there was an uproar over Foxconn motherboards feeding Linux installs incorrect ACPI information (http://ubuntu-virginia.ubuntuforums.org/showthread.php?t=869249).

Foxconn has gladly corrected their mistake, but make sure it's not happening on your motherboard!

After running the command, just view the 'dsdt.dsl' in any editor you like.

cat -n $file | tail -n 100 && head -n number-of-lines-you-want-to-keep > newfile
2009-02-15 01:02:10
User: bbelt16ag
Functions: cat head tail
-1

tells you the number of lines in said file, and then tail the last 100 lines ( or how many are messed up) then u take the total amount of lines and then subract the 100 or so lines u DONT WANT, then do a head -n $new_number and then redirect it to new file.db

cat welcome | wall
2009-02-14 18:12:50
User: Williebee
Functions: cat
-3

Show message in file "welcome" to all logged in terminal users.

cat SomeFile.txt | pbcopy
2009-02-13 15:23:10
Functions: cat
2

Great for little scripts that dig up obscure info that you are going to have to paste into another app anyway.

cat /dev/null >filename
2009-02-13 10:50:41
User: vorphalax
Functions: cat
-8

with this command you can empty file

cat .ssh/id_rsa.pub | ssh hostname 'cat >> .ssh/authorized_keys'
2009-02-11 17:40:12
User: bendavis78
Functions: cat hostname ssh
14

Just run the command, type your password, and that's the last time you need to enter your password for that server.

This assumes that the server supports publickey authentication. Also, the permissions on your home dir are 755, and the permissions on your .ssh dir are 700 (local and remote).

cat file.php | perl -p -e 's/(\$|->)(str|arr|obj|int|flt|boo|bool|mix|res)([A-Z])/$1\L$3/g'
2009-02-10 14:37:12
User: root
Functions: cat perl
0

This removes the type prefix used in Hungarian notation (v. bad) for PHP variables. Eg. variables of the form $intDays, $fltPrice, $arrItems, $objLogger convert to $days, $price, $Items, $logger.

cat -n file.txt
split -b 1k file ; cat x* > file
2009-02-08 23:10:18
User: abcde
Functions: cat file split
2

`split -b 1k file` splits files into 1k chunks. Rejoin them with `cat x* > file`.

cat /proc/<PID>/environ
2009-02-07 20:49:19
User: al3x
Functions: cat
0

Good to find out about hostile processes

cat file.txt|perl -ne '$_=~s/\s+/\n/g; print $_;'
2009-02-06 08:47:18
User: foodie
Functions: cat
-4

This command is useful for separating a text file where all the words are in one line. Any group of spaces will be replaced with a single newline. Instead of one long line of tokens. You'll have a long list of tokens. One token per line.

cat -A
2009-02-06 02:37:51
User: mkc
Functions: cat
0

This is priceless for discovering otherwise invisible characters in files. Like, for example, that stray Control-M at the end of the initial hash bang line in your script, which causes it to generate a mysterious error even though it looks fine.

('od' is the last word, of course, but for many purposes it's much harder to read.)

cat ~/.ssh/id_rsa.pub | ssh user@machine "mkdir ~/.ssh; cat >> ~/.ssh/authorized_keys"
2009-02-05 19:37:56
User: DEinspanjer
Functions: cat ssh
45

If you use Mac OS X or some other *nix variant that doesn't come with ssh-copy-id, this one-liner will allow you to add your public key to a remote machine so you can subsequently ssh to that machine without a password.

cat /proc/cpuinfo
ssh user@host cat /path/to/remotefile | diff /path/to/localfile -
2009-02-04 11:33:19
User: root
Functions: cat diff ssh
145

Useful for checking if there are differences between local and remote files.

cat /etc/issue