Go file

gaojie @Joy :/media/gaojie/Linux/Go/workspace/file$ tree
.
├── bin
│   └── file
├── src
│   ├── file.go
│   └── file.go~
└── tmp
file.goソースは以下の通りです.

package main

import (
	"os"
	"log"
)

func main(){
	if(len(os.Args) < 3){
		log.Fatal("Usage <command> <fileName> [data]");
	}
	log.Printf("args:%s
", os.Args);
	command := os.Args[1];
	fileName :=	os.Args[2];

	//    
	file, err := os.Open(fileName);
    if err != nil {
        log.Println(err)
		file, err = os.Create(fileName);
		if(err != nil){
			log.Fatal(err)
		}
    }

	//      
	fileInfo, _ := file.Stat()
	log.Printf("name:%s, size:%d
", fileInfo.Name(), fileInfo.Size());

	switch command {
		case "read":
			buf := make([]byte, fileInfo.Size())
			readSize, _ := file.Read(buf)
			log.Printf("readSize:%d
", readSize)
			log.Print("bytes:%s
", string(buf));

		case "write":
			if len(os.Args) != 4 {
				MsgExit("Usage: <command> <file> <data>")
			}
			data := os.Args[3];
			writeSize, err := file.WriteString(data);
			if err == nil{
				log.Printf("wirte sucess!%d
", writeSize)
			}
	}


}

func MsgExit( v ...interface{}){
	//fatal        ,      os.Exit(1)     .
	log.Fatal(v)
}

コンパイルと実行

go build -o bin/file src/file.go

gaojie@Joy:/media/gaojie/Linux/Go/workspace/file$ ./bin/file write tmp  gaojie
2013/10/05 15:20:53 args:[./bin/file write tmp gaojie]
2013/10/05 15:20:53 name:tmp, size:3

gaojie@Joy:/media/gaojie/Linux/Go/workspace/file$ ./bin/file read tmp 
2013/10/05 15:20:56 args:[./bin/file read tmp]
2013/10/05 15:20:56 name:tmp, size:3
2013/10/05 15:20:56 readSize:3
2013/10/05 15:20:56 bytes:%s
xxx