GO环境

export GOROOT=$HOME/local/go
export GOPATH=$HOME/go
export PATH=$GOROOT/bin:$GOPATH/bin:$PATH

package main

import "fmt"

func main(){
    fmt.Println("hello golang")
}

[root@db53 go]# GOOS=windows go build hi.go 
[root@db53 go]# ls
hi.exe  hi.go
[root@db53 go]# GOOS=linux go build hi.go 
[root@db53 go]# ll
total 4084
-rwxr-xr-x 1 root root 2034781 Feb 16 15:34 hi
-rwxr-xr-x 1 root root 2139648 Feb 16 15:32 hi.exe
-rw-r--r-- 1 root root      72 Feb 16 15:25 hi.go
[root@db53 go]# chmod +x hi
[root@db53 go]# ./hi
hello golang

curl cip.cc

package main

import (
        "flag"
        "fmt"
        "strings"
)
\\声明一个变量seq      s指定输出结果的分隔符,默认以空格分隔   "separator"是--help显示的内容
var sep = flag.String("s"," ","separator")

func main() {
        flag.Parse()
        fmt.Print(strings.Join(flag.Args(),*sep))
}
\\*sep  取sep的值

[root@db53 go]# go run echo.go --help
Usage of /tmp/go-build774875129/b001/exe/echo:
  -s string
    	separator (default " ")
                   
1%%2%%3[root@db53 go]#  ./echo2 -s - 1 2 3
1-2-3[root@db53 go]# 

package main

import (
        "flag"
        "fmt"
        "strings"
)

var sep = flag.String("s"," ","separator")
var newline = flag.Bool("n",false,"加-n换行")


func main() {
        flag.Parse()
        fmt.Print(strings.Join(flag.Args(),*sep))
        if *newline{
                fmt.Println()
        }
}

import (
    "log"
    "os"
)


func main()  {
//APPEND 代表以追加的方式打开 os.O_CREATE 文件不存在就创建 RDWR 可读可写
    f,err :=os.OpenFile("a.txt",os.O_APPEND|os.O_CREATE|os.O_RDWR,0644)
    if err !=nil {
        log.Fatal(err)


    }
    f.WriteString("hello\n")
    _ = f.Close()
}

package main

import "fmt"

func main() {
	fmt.Print("hello")
	s :="hello"
	n:=4
	fmt.Printf("我的文子是 %s  n=%d\n",s,n)

}

func main() {
   f,err :=os.Create("fmt.txt")
   if err !=nil{
      log.Fatal(err)
   }

   fmt.Fprint(f,"hello")
   s :="hello"
   n:=4
   fmt.Fprintf(f,"我的文子是 %s  n=%d\n",s,n)
    f.Close()
}