Append String to File in Golang

Create Text File

Create new folder named src. In src folder, create new folder named data. In data folder, create new text file named a.txt as below:

Hello World

Application

In src folder, create new file named main.go as below:

package main

import (
	"fmt"
	"os"
)

func main() {

	file, err := os.OpenFile("data/a.txt", os.O_APPEND|os.O_WRONLY, 0666)
	if err != nil {
		fmt.Println(err)
	} else {
		fmt.Fprintln(file, "Hi")
		fmt.Println("Done")
	}
	file.Close()

}

Output

Open Terminal windows in Visual Studio Code and run command line: go run main.go

Done