Select random lines from a file [duplicate]

Question

This question already has an answer here:

• What's an easy way to read random line from a file in Unix command line? 13 answers

In a Bash script, I want to pick out N random lines from input file and output to another file.

How can this be done?

Answer 1

Use shuf with the -n option as shown below, to get N random lines:

shuf -n N input > output

Answer 2

Sort the file randomly and pick first 100 lines:

$ sort -R input | head -n 100 >output