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shuffle.1 revision 1.1 
 $NetBSD: shuffle.1,v 1.1 1998/09/23 21:05:59 perry Exp $

 Copyright (c) 1998
 Perry E. Metzger. All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1. Redistributions of source code must retain the above copyright
 notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
 notice, this list of conditions and the following disclaimer in the
 documentation and/or other materials provided with the distribution.
 3. All advertising materials mentioning features or use of this software
 must display the following acknowledgment:
 This product includes software developed for the NetBSD Project
 by Perry E. Metzger.
 4. The name of the author may not be used to endorse or promote products
 derived from this software without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


.Dd September 22, 1998
.Dt SHUFFLE 1
.Os
.Sh NAME
.Nm shuffle
.Nd print a random permutation of the command line arguments
.Sh SYNOPSIS
.Nm
.Op Fl c Ar arg ...
.Op Fl n Ar number
.Op Fl p Ar number
.Op Ar file
.Sh DESCRIPTION
The
.Nm
program prints a random permutation (or
.Dq shuffle )
of its input lines. This can be useful in shell scripts for selecting a
random order in which to do a set of tasks, view a set of files, etc.

p
If a file name is given as an argument, the file is opened and used as input.

p
If the
.Fl c
option is given, the rest of the arguments on the command line are
shuffled, rather than standard input.

p
If the
.Fl n
option is given, its argument is treated as a number, and the program
prints a random permutation of the numbers greater than or equal to 0
and less than the argument.

p
If the
.Fl p
option is given, its argument is treated as a number, and the program
prints that number of randomly selected lines or arguments in a random order.
.Sh EXAMPLES
d -literal -offset indent $ shuffle -c a b c d
c
b
d
a
$ shuffle -c a b c d
d
b
a
c
$ shuffle -n 4
0
2
1
3
.Ed
.Sh SEE ALSO
.Xr jot 1
.Sh HISTORY
The
.Nm
program first appeared in
.Nx 1.4 .
.Sh AUTHORS
Written by Perry E. Metzger (perry (at] piermont.com).
.Sh BUGS
The random number generator isn't that great, and thus the
permutations often aren't that great.

p
The maximum size of an input line is limited to
.Dv BUFSIZ
from

a Aq stdio.h .
Failures on longer lines are not likely to be pretty.