Go: Append text to a file

This code appends a line of text to the file text.log. It creates the file if it doesn't already exist.

f, err := os.OpenFile("text.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
        log.Println(err)
}
defer f.Close()
        
if _, err := f.WriteString("text to append\n"); err != nil {
        log.Println(err)
}

If you're appending text to a file for logging purposes, see Write log to file.