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.

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.

Universal configuration monitoring and system of record for IT.

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:



May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
March 2, 2015 - New Management
I'm Jon, I'll be maintaining and improving clfu. Thanks to David for building such a great resource!

Top Tags



Psst. Open beta.

Wow, didn't really expect you to read this far down. The latest iteration of the site is in open beta. It's a gentle open beta-- not in prime-time just yet. It's being hosted over at UpGuard (link) and you are more than welcome to give it a shot. Couple things:

  • » The open beta is running a copy of the database that will not carry over to the final version. Don't post anything you don't mind losing.
  • » If you wish to use your user account, you will probably need to reset your password.
Your feedback is appreciated via the form on the beta page. Thanks! -Jon & CLFU Team

Periodically loop a command

Terminal - Periodically loop a command
while true; do ifconfig eth0 | grep "inet addr:"; sleep 60; done;
2009-04-01 19:29:28
User: bandit36
Functions: grep ifconfig sleep
Periodically loop a command

You can use this to loop any command to periodically see the output.

while true; do [YOUR COMMAND HERE]; sleep [# of seconds]; done;

Alternatively, you can put it in a simple shell script to save typing!


while true; do $1; sleep $2; done;

/path/to/script.sh "ifconfig eth0 | grep 'inet addr:'" 60


There is 1 alternative - vote for the best!

Terminal - Alternatives

Know a better way?

If you can do better, submit your command here.

What others think

watch -n1 -d ifconfig eth0

Comment by bartman 421 weeks and 1 day ago

Watch equivalent:

watch -n60 'ifconfig eth0 | grep "inet addr:"'
Comment by SlimG 421 weeks and 1 day ago

Yeah, use watch, if it is available. The best part is that the -d option allows highlighting of the things that have changed since the last invocation. watch is part of the base ubuntu install and comes from the 'procps' package.

Comment by bwoodacre 421 weeks and 1 day ago

Alternatively, there's another really cool alternative to while: until, which negates the condition:

until false;do sleep 1;done

Which actually is handy for things like pinging a down machine

until ping -c1 machine;do sleep 1;done;beep

will make a beep when the machine is back up.

Comment by clockworkavian 421 weeks and 1 day ago

@SlimG- two things: 1) you don't need to nest the command. 2) if you insist on nesting it, for the love of everything good and holy, ditch the backticks.

Comment by atoponce 421 weeks and 1 day ago
while ifconfig eth0 | grep "inet addr:";do sleep 60; done;
Comment by lme 421 weeks and 1 day ago

@atoponce: 1) yes you do or grep won't fire until watch exits. 2) those aren't backticks, they're single quotes; quite different.

Comment by TheMightyBuzzard 421 weeks and 1 day ago

I used it to check my connection since I have some troubles with my ISP (yeah I know I could change...). I put time and date in a file every time my connection is down like this:

while true; do ping pong.sunet.se; date >> downTime; done;
Comment by unixmonkey3130 421 weeks and 1 day ago

Your point of view

You must be signed in to comment.