#!/bin/bash

CADENA=abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789

ARCHIVO=$1
i=1
j=1

while [ $j != 4  ]
do
	
	if [ $j = 1 ]
	then
        	while [ $i != 63  ]
		do
			echo `expr substr $CADENA ${i} 1`
			i=$[i+1]		
		done
	fi

	if [ $j != 1 ]
	then
    		while [ $i != 63  ]
		do
			echo `expr substr $CADENA ${j} 1``expr substr $CADENA ${i} 1`
			i=$[i+1]		
		done
	fi

	j=$[j+1]

done