shuf

Randomly shuffle input lines

TLDR

Shuffle lines of a file

$ shuf [file]

Pick N random lines

$ shuf -n [5] [file]

Generate random numbers in range

$ shuf -i [1-100]

Pick N random numbers from range

$ shuf -i [1-100] -n [10]

Shuffle command arguments

$ shuf -e [item1] [item2] [item3]

Output with custom delimiter

$ shuf -e -z [items] | xargs -0

Repeat output (with replacement)

$ shuf -r -n [10] -e [a] [b] [c]

Use specific random seed

$ shuf --random-source=[/dev/urandom] [file]

SYNOPSIS

shuf [-n count] [-i range] [-e args] [-r] [options] [file]

shuf randomly permutes input lines. It reads input, shuffles the order, and outputs all lines in random sequence.Without options, shuf outputs all input lines in random order. The -n option limits output to the first N lines after shuffling - effectively random sampling without replacement.Input range mode (-i) generates sequential numbers and shuffles them. Combined with -n, this selects random numbers from a range. Useful for generating lottery numbers, random IDs, or sampling.Echo mode (-e) shuffles command-line arguments instead of file lines. This enables shuffling small lists without creating temporary files.Repeat mode (-r) enables sampling with replacement - the same line can appear multiple times in output. This is useful for bootstrap sampling or simulation.The random source option ensures reproducible shuffling when given a deterministic source, useful for testing.

PARAMETERS

-n NUM, --head-count NUM

Output at most NUM lines.

-i LO-HI, --input-range LO-HI

Generate numbers from LO to HI.

-e, --echo

Treat arguments as input lines.

-r, --repeat

Output can repeat (with replacement).

-z, --zero-terminated

Use NUL as line delimiter.

-o FILE, --output FILE

Write to file instead of stdout.

--random-source FILE

Get random bytes from file.

INSTALL

sudo apt install coreutils

sudo dnf install coreutils

sudo pacman -S coreutils

sudo apk add coreutils

sudo zypper install coreutils

brew install coreutils

nix profile install nixpkgs#coreutils

CAVEATS

Loads entire input into memory. Very large files may cause memory issues. Default randomness is good but not cryptographic. Without -n, outputs entire input. Different from sort -R which may group identical lines.

HISTORY

shuf is part of GNU coreutils, providing command-line random shuffling. While Unix systems had various random line selection tools, shuf provides comprehensive shuffling with range generation and sampling options.