Linux shuf command

At least 2-3 times a year I come across a very useful linux command line tool that I think to myself… "How did I not know about this tool, it's so useful!"

This is command 'shuf'  is  one of those tools.

The need

I was writing a simple bash script last night to simply use curl to test out a restful service I am working on.    It’s a restful service that accepts a POST of a JSON file.   I wanted some of the number values in the JSON post to be randomized,  something like 12.34   22.14  some floaty looking number within a narrow range.

Doing a quick google search I came across the command line tool shuf.

Here are a couple of main pages detailing shuf  http://linux.die.net/man/1/shuf [1]

http://manpages.courier-mta.org/htmlman1/shuf.1.html [2]

Here are some basic examples of what it can do.

> shuf -i 10-20

Will generate a list of the integers 10 to 20 inclusive and shuffle them up.

Or for my purposes I just wanted 1 number

> shuf -i 10-20 -n 1

Does the same thing but returns you  a number in the shuffled list

> shuf -i 10-20 -n 3

Returns 3 numbers

For my base script I wanted to create a random number like 12.21  (it was not important that it be really random)

#!/bin/bash for ((i = 0; i < 20; i++)) do    num=`shuf -i 1-20 -n 1`.`shuf -i 1-99 -n 1`    echo $num done

Here are the results of the program running.

[1]        shuf(1) - Linux man page

http://linux.die.net/man/1/shuf  

                Accessed 03/2013

[2]        shuf — generate random permutations

            http://manpages.courier-mta.org/htmlman1/shuf.1.html

                Accessed 03/2013