:
##########################################################################
# Title      :	shuffle - print lines of a file in random order
# Author     :	Heiner Steven <heiner.steven@odn.de>
#		Idea from a script by Chris F.A. Johnson <cfaj@freeshell.org>
# Date       :	2003-07-01
# Requires   :	nawk
# Category   :	File Utilities
# SCCS-Id.   :	@(#) shuffle	1.3 03/07/06
##########################################################################
# Description
#	Shuffles the sequence of lines in a pseudo-random order.
#	Each line is printed exactly once.
##########################################################################

PN=`basename "$0"`			# Program name
VER='1.3'

# We need a "new" awk having srand() and rand(). Examples: GNU awk "gawk",
# Solaris "nawk", or "mawk".
#NAWK=awk

Usage () {
    echo >&2 "$PN - print lines of a file in random order, $VER
usage: $PN [file ...]"
    exit 1
}

Msg () {
    for MsgLine
    do echo "$PN: $MsgLine" >&2
    done
}

Fatal () { Msg "$@"; exit 1; }

searchprog () {
    _search=$1; shift

    for _dir in `echo "$PATH" | sed "s/^:/.:/;s/:\$/:./;s/:/ /g"`
    do
        [ -x "$_dir/$_search" ] || continue
        echo "$_dir/$_search"
        return 0
    done
    return 1
}

while [ $# -gt 0 ]
do
    case "$1" in
	--)	shift; break;;
	-h)	Usage;;
	-*)	Usage;;
	*)	break;;			# First file name
    esac
    shift
done

: ${NAWK:=`searchprog mawk || searchprog gawk || searchprog nawk || echo awk`}
randseed=${RANDOM:-}

"$NAWK" '
    BEGIN { srand('"$randseed"') }	# initialize random number generator
    { print rand() "	" $0 }
' "$@" |
	sort -n |	# Sort numerically on first column
	cut -f2-	# Remove sorting column