Make mkfile accept multiple parameters

cassh.sh

@@ -17,8 +17,8 @@ usage()
 Usage:
 	${0##*/} issue [-hqv] [-I key_id] [-n principals]
 	    [-V validity_interval]
-	${0##*/} mkfile authorized_keys [options]
-	${0##*/} mkfile known_hosts [hostnames]
+	${0##*/} mkfile authorized_keys [options ...]
+	${0##*/} mkfile known_hosts [hostnames ...]
 EOF
 	exit 1
 }
@@ -181,17 +181,11 @@ main_mkfile()
 
 	case $file in
 	authorized_keys)
-		if [ $# -gt 1 ]; then
-			usage
-		fi
-		options=cert-authority${1:+,$1}
+		options=$(printf "%s\n" cert-authority "$@" | paste -sd , -)
 		printf "%s " "$options"
 		;;
 	known_hosts)
-		if [ $# -gt 1 ]; then
-			usage
-		fi
-		hostnames=${1:-}
+		hostnames=$(printf "%s\n" "$@" | paste -sd , -)
 		if [ -n "$hostnames" ]; then
 			printf "@cert-authority %s " "$hostnames"
 		else