#!/bin/sh string=UDFBLR2\' string2=214365 a=0 b=0 for i in `seq 1 25` do rand=$((RANDOM%6+1)) while [ $rand = $a ] || ([ $rand = $b ] && [ $a = `expr substr $string2 $rand 1` ]); do rand=$((RANDOM%6+1)) done b=$a a=$rand var=$var\ `expr substr $string $rand 1` rand=$((RANDOM%3+1)) if [ $rand -gt 0 ]; then rand=$((rand+6)) var=$var`expr substr $string $rand 1` fi done echo $var