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.

UpGuard checks and validates configurations for every major OS, network device, and cloud provider.

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



extract email adresses from some file (or any other pattern)

Terminal - extract email adresses from some file (or any other pattern)
grep -Eio '([[:alnum:]_.-][email protected][[:alnum:]_.-]+?\.[[:alpha:].]{2,6})'
2009-11-22 21:14:49
User: fooBier
Functions: grep
extract email adresses from some file (or any other pattern)

Simply more email-adresses matched


There is 1 alternative - vote for the best!

Terminal - Alternatives
grep -Eio '([[:alnum:]_.][email protected][[:alnum:]_]+?\.[[:alpha:].]{2,6})' file.html
2009-06-16 20:19:47
User: wires
Functions: grep

find all email addresses in a file, printing each match. Addresses do not have to be alone on a line etc. For example you can grab them from HTML-formatted emails or CSV files, etc. Use a combination of


to filter them.

grep -aEio '([[:alnum:]_.-\+\-][email protected][[:alnum:]_.-]+?\.[[:alpha:].]{2,6})'
2013-06-23 21:52:14
User: binarynomad
Functions: grep
Tags: grep email

This will catch most separators in the section of the email:

dot .

dash -

underscore _

plus + (added for gmail)

... and the basic dash '-' of host names.

grep -aEio '([[:alnum:]_.-][email protected][[:alnum:]_.-]+?\.[[:alpha:].]{2,6})'
2013-05-30 07:17:32
User: nabil_kadimi
Functions: grep

The -a option in -aEio tells grep to treat binary files as text files.

Know a better way?

If you can do better, submit your command here.

What others think

People really should take the time to read RFC822 and RFC1035.

This regex is too limited in the username (e.g., plus signs are valid) and too permissive in the domain name (underscores are not valid).

To see how insane it is to try and create a single regex that correctly validates RFC822-compliant email addresses, here's one: http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html

I'd rather see a regex that was too permissive in the username and correct in the domain name. That way it's more likely to catch valid email addresses and bypass false positives.

Comment by KlfJoat 208 weeks and 1 day ago

Your point of view

You must be signed in to comment.