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 X

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

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.

Alternatives

There are 2 alternatives - vote for the best!

Terminal - Alternatives
od -An -N1 -tu1 /dev/random
2013-09-10 08:57:16
User: sucotronic
Functions: od
6

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

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

The $[] form is deprecated. Use $(()) instead.

Comment by dennisw 219 weeks and 4 days ago

This is simple, but not sh compatible.

Just bash compatible.

Il prefer the awk version.

Comment by dooblem 219 weeks and 2 days ago

num-utils has a 'random' function where you just have to do:

random 1..5
Comment by matthewbauer 219 weeks and 2 days ago

The solution is wrong, or at least not well explained, because X have to be lower than 32767 (see man bash)

The awk version is ok, but you've to know that the seed generation is based in clock, so if you ask for numbers in a certain interval, you'll get the same numbers!!

num-utils package contains numrandom command, but it is not very efficient, because it generates a list of numbers and then picks one :P

Comment by sucotronic 58 weeks and 2 days ago

how can i give x like an argument betweeen 100-100000

Comment by gerih26 40 weeks and 2 days ago

Your point of view

You must be signed in to comment.

Related sites and podcasts