Read a character from user then determine whether it is uppercase letter, lower case letter or digit using Linux shell script in Ubuntu
echo "Enter any character : "
read c
case $c in
([[:lower:]]) echo lower case;;
([[:upper:]]) echo upper case;;
([[:digit:]]) echo digit;;
esac
read c
case $c in
([[:lower:]]) echo lower case;;
([[:upper:]]) echo upper case;;
([[:digit:]]) echo digit;;
esac