如何使用go脚本创建新文件

Question

I am new to go lang. I am able to create a new file from the terminal using go script. like this

go run ../myscript.go > ../filename.txt

but I want to create the file from the script.

package main

import "fmt"

func main() {
    fmt.Println("Hello") > filename.txt
}

Answer 1

If you are trying to print some text to a file one way to do it is like below, however if the file already exists its contents will be lost:

package main

import (
    "fmt"
    "io/ioutil"
)

func main() {
    err := ioutil.WriteFile("filename.txt", []byte("Hello"), 0755)
    if err != nil {
        fmt.Printf("Unable to write file: %v", err)
    }
}

The following way will allow you to append to an existing file if it already exists, or creates a new file if it doesn't exist:

package main

import (
    "os"
    "log"
)


func main() {
    // If the file doesn't exist, create it, or append to the file
    f, err := os.OpenFile("access.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
    if err != nil {
        log.Fatal(err)
    }

    _, err = f.Write([]byte("Hello"))
    if err != nil {
        log.Fatal(err)
    }

    f.Close()
}

Answer 2

you just need to check the API documentation. This is one way to do it, there is others (with os or bufio )

package main

import (
    "io/ioutil"
)

func main() {
    // read the whole file at once
    b, err := ioutil.ReadFile("input.txt")
    if err != nil {
        panic(err)
    }

    // write the whole body at once
    err = ioutil.WriteFile("output.txt", b, 0644)
    if err != nil {
        panic(err)
    }
}

Answer 3

Fprintln is pretty close to what you were trying to do:

package main

import (
   "fmt"
   "os"
)

func main() {
   f, e := os.Create("filename.txt")
   if e != nil {
      panic(e)
   }
   defer f.Close()
   fmt.Fprintln(f, "Hello")
}

https://golang.org/pkg/fmt#Fprintln