#!/bin/tcsh# Demonstration of a switch control structure.# This routine tests the first command-line argument# for yes or no in any combination of upper and# lowercase letters.## test that argv[1] existsif ($#argv != 1) then	echo "Usage: switch_1 [yes|no]"	exit 1else# argv[1] exists, set up switch based on its value	switch ($argv[1])	# case of YES		case [yY][eE][sS]:		echo "Argument one is yes."		breaksw	#	# case of NO		case [nN][oO]:		echo "Argument one is no."	breaksw	#	# default case		default:		echo "Argument one is neither yes nor no."		breaksw	endswendif