shuf

Coreutils: https://www.gnu.org/software/coreutils/manual/html_node/shuf-invocation.html

Generate a random permutation of the input lines:

printf 'a\nb\nc\nd\n' | shuf

Possible output:

d
a
c
b

i

Generate a random permutation of the range {1..4}:

shuf -i1-4

Special case: generate one random integer in range:

shuf -i1-4 -n1

Alternatives

Depending on the use case:

• Bash built-in RANDOM
• /dev/random