Initial approach

command/chain_watch.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/command/flagset"
+	"github.com/ethereum/go-ethereum/command/server/proto"
+)
+
+// ChainWatchCommand is the command to group the peers commands
+type ChainWatchCommand struct {
+	*Meta2
+}
+
+// Help implements the cli.Command interface
+func (c *ChainWatchCommand) Help() string {
+	return ``
+}
+
+func (c *ChainWatchCommand) Flags() *flagset.Flagset {
+	flags := c.NewFlagSet("chain watch")
+
+	return flags
+}
+
+// Synopsis implements the cli.Command interface
+func (c *ChainWatchCommand) Synopsis() string {
+	return ""
+}
+
+// Run implements the cli.Command interface
+func (c *ChainWatchCommand) Run(args []string) int {
+	flags := c.Flags()
+	if err := flags.Parse(args); err != nil {
+		c.UI.Error(err.Error())
+		return 1
+	}
+
+	borClt, err := c.BorConn()
+	if err != nil {
+		c.UI.Error(err.Error())
+		return 1
+	}
+
+	sub, err := borClt.ChainWatch(context.Background(), &proto.ChainWatchRequest{})
+	if err != nil {
+		panic(err)
+	}
+
+	for {
+		msg, err := sub.Recv()
+		if err != nil {
+			// if err == EOF if finished on the other side
+			panic(err)
+		}
+		fmt.Println("message received")
+		fmt.Println(msg)
+	}
+
+	return 0
+}

command/main.go

@@ -69,6 +69,11 @@ func commands() map[string]cli.CommandFactory {
 				UI: ui,
 			}, nil
 		},
+		"chain watch": func() (cli.Command, error) {
+			return &ChainWatchCommand{
+				Meta2: meta2,
+			}, nil
+		},
 		"chain sethead": func() (cli.Command, error) {
 			return &ChainSetHeadCommand{
 				Meta2: meta2,