# is_num() -- Check if input is number between 0-9
# Usage: is_num input
#
# Example:
#
# if is_num 200; then
#	echo "OK";
# fi
#

is_num() {
	[ $# -eq 1 ] || return 1;
	[[ $1 =~ ^([0-9]+)$ ]] && return 0;
	return 1;
}