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.

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:

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

Tags

Hide

Functions

Random Number Between 1 And 256

Terminal - Random Number Between 1 And 256
od -An -N1 -tu1 /dev/random
2013-09-10 08:57:16
User: sucotronic
Functions: od
6
Random Number Between 1 And 256

It takes a byte from /dev/random whose source is the kernel entropy pool (better source than other solutions).

Alternatives

There are 2 alternatives - vote for the best!

Terminal - Alternatives
echo $[RANDOM%X+1]
2010-08-07 02:43:46
Functions: echo
24

If X is 5, it will about a number between 1 and 5 inclusive.

This works in bash and zsh.

If you want between 0 and 4, remove the +1.

awk 'BEGIN { srand(); print rand() }'
2010-08-07 14:33:12
User: dennisw
Functions: awk
Tags: random number
-2

2d6 dice:

awk 'BEGIN { srand(); a=int(rand()*6)+1; b=int(rand()*6)+1; print a " + " b " = " a+b }'

3 + 6 = 9

echo "$(od -An -N4 -tu4 /dev/urandom) % 5 + 1" | bc
2010-08-10 12:10:21
User: dooblem
Functions: echo
-4

This is /bin/sh compatible.

Know a better way?

If you can do better, submit your command here.

What others think

Wonderful.

Share a website with you ,

( http://www.shoes2.us// )

Believe you will love it.

We accept any form of payment.

http://www.shoes2.us/Michael-Kors-Handbags-n2447/

Comment by shoesus30 53 weeks and 2 days ago

Wonderful.

Share a website with you ,

( http://www.shoes2.us// )

Believe you will love it.

We accept any form of payment.

http://www.shoes2.us/Michael-Kors-Handbags-n2447/

Comment by shoesus30 53 weeks and 2 days ago

Unless you know you need it (and for small ints you don't), /dev/urandom is the better choice to use in programs:

Reading /dev/random can block other programs from getting entropy! (see https://en.wikipedia.org/wiki/Urandom)

Comment by zvyn 53 weeks and 2 days ago

zvyn > of course this is not intended to be used in a iterative script, I only wanted a 'true' random number (or the thing more near to it)

Comment by sucotronic 53 weeks and 2 days ago

Your point of view

You must be signed in to comment.

Related sites and podcasts