tail add -n and -f

README.md

@@ -24,7 +24,7 @@ Go version at least `1.4`
 	$ gosuv stop timetest
 	program "timetest" stopped
 
-	$ gosuv tail timetest
+	$ gosuv tail -n 2 -f timetest
 	line 1
 	line 2
 	line ...

gosuv.go

@@ -166,7 +166,11 @@ func StopAction(ctx *cli.Context) {
 }
 
 func TailAction(ctx *cli.Context, client pb.ProgramClient) {
-	req := &pb.Request{Name: ctx.Args().First()}
+	req := &pb.TailRequest{
+		Name:   ctx.Args().First(),
+		Number: int32(ctx.Int("number")),
+		Follow: ctx.Bool("follow"),
+	}
 	tailc, err := client.Tail(context.Background(), req)
 	if err != nil {
 		log.Fatal(err)
@@ -300,6 +304,17 @@ func initCli() {
 			Name:   "tail",
 			Usage:  "tail log",
 			Action: wrap(TailAction),
+			Flags: []cli.Flag{
+				cli.IntFlag{
+					Name:  "number, n",
+					Value: 10,
+					Usage: "The location is number lines.",
+				},
+				cli.BoolFlag{
+					Name:  "follow, f",
+					Usage: "Constantly show log",
+				},
+			},
 		},
 		{
 			Name:   "shutdown",

gosuvpb/gosuv.pb.go

@@ -12,6 +12,7 @@ It has these top-level messages:
 	NopRequest
 	Response
 	Request
+	TailRequest
 	ProgramInfo
 	ProgramStatus
 	StatusResponse
@@ -57,6 +58,16 @@ func (m *Request) Reset()         { *m = Request{} }
 func (m *Request) String() string { return proto.CompactTextString(m) }
 func (*Request) ProtoMessage()    {}
 
+type TailRequest struct {
+	Name   string `protobuf:"bytes,1,opt,name=name" json:"name,omitempty"`
+	Number int32  `protobuf:"varint,2,opt,name=number" json:"number,omitempty"`
+	Follow bool   `protobuf:"varint,3,opt,name=follow" json:"follow,omitempty"`
+}
+
+func (m *TailRequest) Reset()         { *m = TailRequest{} }
+func (m *TailRequest) String() string { return proto.CompactTextString(m) }
+func (*TailRequest) ProtoMessage()    {}
+
 type ProgramInfo struct {
 	Name    string `protobuf:"bytes,1,opt,name=name" json:"name,omitempty"`
 	Command string `protobuf:"bytes,2,opt,name=command" json:"command,omitempty"`
@@ -220,7 +231,7 @@ var _GoSuv_serviceDesc = grpc.ServiceDesc{
 type ProgramClient interface {
 	Start(ctx context.Context, in *Request, opts ...grpc.CallOption) (*Response, error)
 	Stop(ctx context.Context, in *Request, opts ...grpc.CallOption) (*Response, error)
-	Tail(ctx context.Context, in *Request, opts ...grpc.CallOption) (Program_TailClient, error)
+	Tail(ctx context.Context, in *TailRequest, opts ...grpc.CallOption) (Program_TailClient, error)
 }
 
 type programClient struct {
@@ -249,7 +260,7 @@ func (c *programClient) Stop(ctx context.Context, in *Request, opts ...grpc.Call
 	return out, nil
 }
 
-func (c *programClient) Tail(ctx context.Context, in *Request, opts ...grpc.CallOption) (Program_TailClient, error) {
+func (c *programClient) Tail(ctx context.Context, in *TailRequest, opts ...grpc.CallOption) (Program_TailClient, error) {
 	stream, err := grpc.NewClientStream(ctx, &_Program_serviceDesc.Streams[0], c.cc, "/gosuvpb.Program/Tail", opts...)
 	if err != nil {
 		return nil, err
@@ -286,7 +297,7 @@ func (x *programTailClient) Recv() (*LogLine, error) {
 type ProgramServer interface {
 	Start(context.Context, *Request) (*Response, error)
 	Stop(context.Context, *Request) (*Response, error)
-	Tail(*Request, Program_TailServer) error
+	Tail(*TailRequest, Program_TailServer) error
 }
 
 func RegisterProgramServer(s *grpc.Server, srv ProgramServer) {
@@ -318,7 +329,7 @@ func _Program_Stop_Handler(srv interface{}, ctx context.Context, codec grpc.Code
 }
 
 func _Program_Tail_Handler(srv interface{}, stream grpc.ServerStream) error {
-	m := new(Request)
+	m := new(TailRequest)
 	if err := stream.RecvMsg(m); err != nil {
 		return err
 	}

gosuvpb/gosuv.proto

@@ -13,6 +13,11 @@ message Request {
   string name = 1;
 }
 
+message TailRequest {
+  string name = 1;
+  int32 number = 2; // the location of number lines
+  bool follow = 3;
+}
 message ProgramInfo {
   string name = 1;
   string command = 2;
@@ -42,5 +47,5 @@ service GoSuv {
 service Program {
   rpc Start(Request) returns (Response) {}
   rpc Stop(Request) returns (Response) {}
-  rpc Tail(Request) returns (stream LogLine) {}
+  rpc Tail(TailRequest) returns (stream LogLine) {}
 }

service.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"net"
 	"os"
 	"os/exec"
@@ -36,12 +37,16 @@ func (this *PbProgram) Stop(ctx context.Context, in *pb.Request) (res *pb.Respon
 }
 
 //func (this *PbProgram) Tail(ctx context.Context, in *pb.Request)(stream
-func (c *PbProgram) Tail(in *pb.Request, stream pb.Program_TailServer) (err error) {
+func (c *PbProgram) Tail(in *pb.TailRequest, stream pb.Program_TailServer) (err error) {
 	program, err := programTable.Get(in.Name)
 	if err != nil {
 		return
 	}
-	cmd := exec.Command("tail", "-n5", "-f", program.logFilePath())
+	args := []string{"-n", fmt.Sprintf("%d", in.Number)}
+	if in.Follow {
+		args = append(args, "-f")
+	}
+	cmd := exec.Command("tail", append(args, program.logFilePath())...)
 	rd, err := cmd.StdoutPipe()
 	go cmd.Run()
 	defer func() {