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shuf shuffles its input by outputting a random permutation of its input lines. Each output permutation is equally likely. Synopses:
shuf [option]... [file] shuf -e [option]... [arg]... shuf -i lo-hi [option]...
shuf has three modes of operation that affect where it obtains its input lines. By default, it reads lines from standard input. The following options change the operation mode:
shuf's other options can affect its behavior in all operation modes:
shuf -o F <Fand
cat F | shuf -o F.
shuf <<EOF A man, a plan, a canal: Panama! EOF
might produce the output
Panama! A man, a canal: a plan,
Similarly, the command:
shuf -e clubs hearts diamonds spades
clubs diamonds spades hearts
and the command ‘shuf -i 1-4’ might output:
4 2 1 3
These examples all have four input lines, so shuf might produce any of the twenty-four possible permutations of the input. In general, if there are n input lines, there are n! (i.e., n factorial, or n * (n - 1) * ... * 1) possible output permutations.
An exit status of zero indicates success, and a nonzero value indicates failure.