Shell script to convert string lower to upper and upper to lower

SCRIPT:

#!/bin/bash
echo -n "enter any string in lowercase : "
read l_str
u_str=`echo $l_str | tr [a-z] [A-Z]`
echo "lower to upper converted o/p : $u_str"

echo -n "enter any string in uppercase : "
read u_str
l_str=`echo $u_str | tr [A-Z] [a-z]`
echo "upper to lower converted o/p : $l_str"

OUTPUT:

sujin@sujin:~/work/shell$ bash lwr2upr.sh
enter any string in lowercase : cricket
lower to upper converted o/p : CRICKET
enter any string in uppercase : FOOTBALL
upper to lower converted o/p : football