All commands (14,187)

What's this?

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

Share Your Commands


Check These Out

Is it a terminal?
Oddly, the isatty(3) glibc C call doesn't have a direct analogue as a command 'isatty(1)'. All is not lost as you can use test(1). For example, your script might be run from a tty or from a GUI menu item but it needs to get user-input or give feedback. Now your script can test STDIN with 'isatty 0' or STDOUT with 'isatty 1' and use xmessage(1) if the tty is not available. The other way to test for this is with 'tty -s' - but that's only for STDIN.

find out how much space are occuipied by files smaller than 1024K (sic) - improved
The original didn't use -print0 which fails on weird file names eg with spaces. The original parsed the output of 'ls -l' which is always a bad idea.

detach remote console for long running operations
Starts midnightcommander and allows you to detach the console; use ctrl-\ to detach Then at a later time you can reconnect using $ dtach -a /tmp/wires-mc In my experience dtach works much better for programs like irssi, mutt, mc, aptitude than screen does.

Are the two lines anagrams?
This works by reading in two lines of input, turning each into a list of one-character matches that are sorted and compared.

add a backup (or any other) suffix to a file
Very helpful when you've got complex filenames and needs to change just some small parts of it. Renaming a file called "i-made-a-small-typo-right-here" to "i-made-a-big-typo-right-here": $ mv -vi i-made-a-{small,big}-typo-right-here You could also copy multiple files, edit, remove, process, etc.

Url Encode
Returns URL Encoded string from input ($1).

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

List the most recent dates in reverse-chronological order
bash brace expansion, sequence expression

Create a backup of the file.
It will create a backup of the filename. The advantage is that if you list the folder the backups will be sorted by date. The command works on any unix in bash.

Find processes stuck in dreaded "D" state aka IO Wait
Lots of fun to run on nfs clients when the server or network connection is having issues


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: