support unix sockets (#26)

cmd/grpcurl/unix.go

@@ -0,0 +1,16 @@
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package main
+
+import "flag"
+
+var (
+	unix = flag.Bool("unix", false,
+		`Indicates that the server address is the path to a Unix domain socket.`)
+)
+
+func init() {
+	isUnixSocket = func() bool {
+		return *unix
+	}
+}