How to Append Text to a File in Go?

Appending to a File in Go

To write to a file in Go, you can use the ioutil.WriteFile function. However, if you want to append to a file, this function cannot be used. Instead, you can leverage the os.OpenFile function with the os.O_APPEND flag.

Here's how to append to a file in Go:

import (
    "fmt"
    "os"
)

func main() {
    filename := "myfile.txt"
    text := "New text to be appended\n"

    f, err := os.OpenFile(filename, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
    if err != nil {
        fmt.Println(err)
        return
    }

    defer f.Close()

    if _, err = f.WriteString(text); err != nil {
        fmt.Println(err)
        return
    }
}

In this code:

• We open the file with the O_APPEND flag, which ensures that new data will be appended at the end of the existing file.
• We also set the O_WRONLY flag to indicate that we will only be writing to the file.
• We set the O_CREATE flag to indicate that the file should be created if it doesn't exist.
• We use the f.WriteString method to append the provided text to the end of the file.
• Remember to defer closing the file after the operation is complete.

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