Refactor: join strings in shell instead of relying on paste

cassh.sh

@@ -92,6 +92,19 @@ format()
 	echo "$_out"
 }
 
+strjoin()
+{
+	_c=$1
+	shift
+
+	_out=
+	for _s; do
+		_out=${_out:+$_out$_c}$_s
+	done
+
+	echo "$_out"
+}
+
 main_issue()
 {
 	hflag=
@@ -175,13 +188,11 @@ main_mkfile()
 
 	case $file in
 	authorized_keys)
-		options=$(printf "%s\n" cert-authority "$@" | paste -sd , -)
-		printf "%s " "$options"
+		printf "%s " "$(strjoin , cert-authority "$@")"
 		;;
 	known_hosts)
-		hostnames=$(printf "%s\n" "$@" | paste -sd , -)
-		if [ -n "$hostnames" ]; then
-			printf "@cert-authority %s " "$hostnames"
+		if [ $# -gt 0 ]; then
+			printf "@cert-authority %s " "$(strjoin , "$@")"
 		else
 			printf "@cert-authority "
 		fi