add ipc example

README.md

@@ -1,2 +1,110 @@
 # ipc
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/hslam/ipc)](https://pkg.go.dev/github.com/hslam/ipc)
+[![Go Report Card](https://goreportcard.com/badge/github.com/hslam/ipc)](https://goreportcard.com/report/github.com/hslam/ipc)
+[![LICENSE](https://img.shields.io/github/license/hslam/ipc.svg?style=flat-square)](https://github.com/hslam/ipc/blob/master/LICENSE)
+
 Package ipc provides a way to use System V IPC. System V IPC includes three interprocess communication mechanisms that are widely available on UNIX systems: message queues, semaphore, and shared memory.
+
+## Get started
+
+### Install
+```
+go get github.com/hslam/ipc
+```
+### Import
+```
+import "github.com/hslam/ipc"
+```
+### Usage
+####  Example
+```go
+package main
+
+import (
+	"encoding/binary"
+	"flag"
+	"fmt"
+	"github.com/hslam/ipc"
+	"os"
+	"os/signal"
+	"syscall"
+)
+
+var send = flag.Bool("s", true, "send")
+
+func main() {
+	key, _ := ipc.Ftok("/tmp", 0x22)
+	semid, _ := ipc.Semget(key)
+	defer ipc.Semrm(semid)
+	shmid, data, _ := ipc.Shmgetat(key, 128, ipc.IPC_CREAT|0600)
+	defer ipc.Shmrm(shmid)
+	defer ipc.Shmdt(data)
+	msgid, _ := ipc.Msgget(key, ipc.IPC_CREAT|0600)
+	defer ipc.Msgrm(msgid)
+	var text string
+	quit := make(chan os.Signal)
+	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		defer close(quit)
+		if *send {
+			fmt.Println("Enter:")
+			buf := make([]byte, 10)
+			for {
+				fmt.Scanln(&text)
+				if _, err := ipc.Semp(semid, ipc.SEM_UNDO); err != nil {
+					return
+				}
+				copy(data, text)
+				if _, err := ipc.Semv(semid, ipc.SEM_UNDO); err != nil {
+					return
+				}
+				n := binary.PutUvarint(buf, uint64(len(text)))
+				if err := ipc.Msgsnd(msgid, 1, buf[:n], 0600); err != nil {
+					return
+				}
+			}
+		} else {
+			fmt.Println("Recv:")
+			for {
+				m, err := ipc.Msgrcv(msgid, 1, 0600)
+				if err != nil {
+					return
+				}
+				length, _ := binary.Uvarint(m)
+				if _, err := ipc.Semp(semid, ipc.SEM_UNDO); err != nil {
+					return
+				}
+				text = string(data[:length])
+				if _, err := ipc.Semv(semid, ipc.SEM_UNDO); err != nil {
+					return
+				}
+				fmt.Println(text)
+			}
+		}
+	}()
+	<-quit
+}
+```
+
+#### Output
+Enter a word.
+```sh
+$ go run main.go -s true
+Enter:
+HelloWorld
+```
+In another terminal receive this word.
+```sh
+$ go run main.go -s false
+Recv:
+HelloWorld
+```
+
+### License
+This package is licensed under a MIT license (Copyright (c) 2020 Meng Huang)
+
+
+### Author
+ipc was written by Meng Huang.
+
+