Copy

There's no unique function that makes it possible to copy a file, but this can easily be done with a reader and a writer with the io.Copy function. The following example shows how to use it to copy from one file to another:

func CopyFile(from, to string) (int64, error) {
    src, err := os.Open(from)
    if err != nil {
        return 0, err
    }
    defer src.Close()
    dst, err := os.OpenFile(to, os.O_WRONLY|os.O_CREATE, 0644)
    if err != nil {
        return 0, err
    }
    defer dst.Close()  
    return io.Copy(dst, src)
}