shuf Linux Command Guide

The shuf command in Linux is used to generate random permutations of input lines. It can shuffle the contents of a file or produce a random sample from a list. By default, shuf outputs a random permutation of the input. Users can specify the number of output lines using the -n option. Additional options allow users to set a seed for the random generator, specify a range of randomizations, and more. This command is useful for randomizing the order of lines in a file or selecting random items from a list.

shuf Syntax:

shuf [option] [input_file]

Options:

Option	Description
-e	Treat each argument as an input line
-i	Generate random numbers within a specified range
-n	Output at most N lines
-r	Allow repeated lines in the output
-z	Delimit items with a NUL (‘\0’) byte

Parameters:

Parameter	Description
input_file	Specify the input file. If not provided, uses stdin

Caution

Exercise caution especially when using the -r option, as it can lead to duplication of lines in the output which might not be desired. Always double-check the options used to avoid unexpected behavior.

shuf Command Samples:

Shuffle Lines in a File

shuf file.txt

Randomizes the order of lines in the file.txt.

Shuffle a List of Numbers

shuf -e 1 2 3 4 5

Randomly shuffles the list of numbers 1, 2, 3, 4, and 5.

Generate a Random Permutation

shuf -e a b c d e

Produces a random permutation of the elements a, b, c, d, and e.

Shuffle Lines and Output Only N Lines

shuf -n 3 file.txt

Shuffles the lines in file.txt and prints only 3 lines.

Shuffle and Pick Randomly From a List

shuf -n 2 -e apple orange banana mango

Shuffles the fruits list and selects 2 random items.

Shuffle and Redirect to a New File

shuf names.txt > shuffled_names.txt

Randomly shuffles the lines in names.txt and saves the output to shuffled_names.txt.

Shuffle and Limit Randomization by Seed

shuf -n 4 --random-source=/dev/urandom file.txt

Shuffles file.txt using /dev/urandom as the seed and selects 4 random lines.

Tip

When using the shuf command in Linux, make sure to read the man page (man shuf) to fully understand all available options and how to use them effectively. Additionally, remember to redirect the shuf output to a file or use it within a pipeline to further process the shuffled data.

shuf FAQ:

How do I use shuf in Linux?

To use the shuf command in Linux, execute the following command:

shuf <file>

What is the purpose of shuf in Linux?

The purpose of the shuf command in Linux is to generate random permutations of input lines.

How can I shuffle multiple files with shuf?

You can shuffle multiple files using shuf by providing them as arguments to the command. Here is an example:

shuf file1.txt file2.txt

Can I limit the number of lines shuffled with shuf in Linux?

Yes, you can limit the number of lines shuffled with shuf by using the -n or --head-count option followed by the number of lines. Here is an example:

shuf -n 10 file.txt

How can I shuffle lines and then select a specific number of lines with shuf?

To shuffle lines and then select a specific number of lines with shuf, you can combine the -n option with the command. Here is an example:

shuf file.txt -n 5

Is there a way to avoid repeating shuffled lines in shuf?

Yes, you can prevent shuf from repeating shuffled lines by using the -r or --repeat option. This will shuffle lines and print them in a random order without repeating any line until all lines have been printed at least once.

Applications of the shuf command

• Generating randomized quiz questions
• Shuffling the order of lines in a text file
• Randomly selecting winners in a contest
• Creating shuffled playlists
• Generating random test data for software testing