chk_name() {
	# return with error 1 if parameters mismatch
	[ $# = 2 ] || {
		echo "chk_name: Error: parameter mismatch."
		return 1
	}
	# return with error 2 if invalid device name given
	echo $1 | sed "s/^$2[0-9][0-9]*$//"\
	| grep -Eq '.+' && {
	    echo "chk_name: Error: $1 is no a valid $2 device name."
	    return 2
	}
	return 0
}
