05-b-2800 3rd sol.sh

#!/bin/bash
# 05-b-2800 3rd solution

if [ $# -ne 1 ]; then
	echo "Invalid number of arguments!"
	exit 1
elif grep -qE '^[[:alnum:]]+$' <(echo "${1}"); then
	echo "True"
	exit 0
else
	echo "False"
	exit 1
fi