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.


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.
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

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!
Hide

Top Tags

Hide

Functions

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

Generate random password

Terminal - Generate random password
dd bs=1 count=32 if=/dev/random 2> /dev/null | md5 | grep -o '\w*'
2009-02-15 23:22:46
User: neW1
Functions: dd grep
-5
Generate random password

Alternatives

There are 8 alternatives - vote for the best!

Terminal - Alternatives
strings /dev/urandom | grep -o '[[:alnum:]]' | head -n 30 | tr -d '\n'; echo
2009-02-16 00:39:28
User: jbcurtis
Functions: grep head strings tr
49

Find random strings within /dev/urandom. Using grep filter to just Alphanumeric characters, and then print the first 30 and remove all the line feeds.

pwgen -Bs 10 1
2009-12-01 14:33:51
15

-B flag = don't include characters that can be confused for other characters (this helps when you give someone their password for the first time so they don't cause a lockout with, for example, denyhosts or fail2ban)

-s flag = make a "secure", or hard-to-crack password

-y flag = include special characters (not used in the example because so many people hate it -- however I recommend it)

"1 10" = output 1 password, make it 10 characters in length

For even more secure passwords please use the -y flag to include special characters like so:

pwgen -Bsy 10 1

output>> }&^Y?.>7Wu

< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c6
2009-02-24 09:43:40
User: Blackbit
Functions: head tr
11

If you want a password length longer than 6, changing the -c6 to read -c8 will give you 8 random characters instead of 6. To end up with a line-feed, use this with echo:

# echo `< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c6`

randpw(){ < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c${1:-16};echo;}
2009-08-07 07:30:57
User: frozenfire
Functions: head tr
3

Generates password consisting of alphanumeric characters, defaults to 16 characters unless argument given.

dd if=/dev/urandom bs=1 count=32 2>/dev/null | base64 -w 0 | rev | cut -b 2- | rev
2009-02-17 23:36:24
User: TyIzaeL
Functions: cut dd rev
0

I know there are a lot of random password generators out there, but I wanted something that put out something besides hex. Set count equal to the number of bytes you want.

Know a better way?

If you can do better, submit your command here.

Your point of view

You must be signed in to comment.