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

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:

» all commands
» commands with 3 up-votes (commandlinefu3)
» commands with 10 up-votes (commandlinefu10)
» commands by wipu

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

Functions

Hide

Credits

Site by David Winterbottom (user root).

Commands by wipu

Terminal - Commands by wipu - 4 results

quietly() { "$@" > /dev/null 2>&1; }

2011-10-04 06:45:42

User: wipu

Tags: redirection function parameter expansion

Up
Down

Suppress output of loud commands you don't want to hear from

This works even if there are spaces in any word in the command line.

(set -e; while true; do TEST_COMMAND; done) | tee log

2011-09-06 12:29:11

User: wipu

Functions: set tee

Tags: tee while set

-3

Up
Down

Reproduce test failure by running the test in loop

If you need to fix a randomly failing test (race condition), you need to run it until you get that hard-to-reproduce failure.

(echo 0; find [args...] -printf '%s +\n'; echo p) | dc

2011-08-17 07:49:55

User: wipu

Functions: echo find

-1

Up
Down

Sum size of files returned from FIND

Just an alternative. Here the output of the subshell statement is a complete script for dc so you can save it, manipulate it with some other tool or just debug it with less.

Comments (0) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate

set -eu

2010-04-07 11:54:40

User: wipu

Functions: set

Up
Down

Robust expansion (i.e. crash) of bash variables with a typo

By default bash expands an unbound variable to an empty string. This can be dangerous, if a critical variable name (a path prefix for example) has a typo. The -u option causes bash to treat this as an error, and the -e option causes it to exit in case of an error. These two together will make your scripts a lot safer against typos.

The default behaviour can be explicitly requested using the ${NAME:-} syntax.

A (less explicit) variation: #!/bin/bash -eu