What is the shuf command in UNIX?

The shuf command generates random permutations from input lines to standard output. If given a file or series of files it will shuffle the lines and write the result to standard output. It can also limit the number of results returned supporting selecting random lines from a file or data from a list.

How to shuffle the contents of a file

To shuffle the lines in a file using the shuf command pass a file, files or standard input to the command. The result will be printed to standard output. In the following example we have a list of cards in a file saved ascards.txt. This file is ordered by suit and number.

shuf cards.txt

4D

9D

QC

3S

6D

The shuf command shuffles the lines and outputs this to standard output.

How to pick a random line from a file

To pick a random line from a file using shuf use the -n option. This limits the output to the number specified.

shuf -n 1 cards.txt

KH

To select more than one line change the number.

shuf -n 5 cards.txt

4H

9S

KH

9D

9H

How to shuffle standard input

To shuffle words passed to shuf in standard input use the -e option. This shuffles items separated by spaces.

shuf -e one two three

three 

two 

one

If you wanted to quickly decide whose turn it is to make the tea you can useshuf.

shuf -n 1 -e George Kirsten Fin Bea

Bea

Bea make the tea!