How to Copy a File in Go

Created May 9, 2022 at 8:47

Modified May 9, 2022 at 8:59

Using io.Copy Function

You can copy a file using the io.Copy() function. For example,

package main

import (
  "io"
  "os"
)

// Copy the src file to dst.
func Copy(src, dst string) error {

  in, err := os.Open(src)
  if err != nil {
    return err
  }
  defer in.Close()

  out, err := os.Create(dst)
  if err != nil {
    return err
  }

  _, err = io.Copy(out, in)
  if err != nil {
    return err
  }

  return nil
}

func main() {
  Copy("access.log", "access.1.log")
}

access.1.log

Using ioutil.WriteFile Function

The following example should cover whatever you are trying to do:

package main

import (
  "io/ioutil"
)

// Copy the src file to dst.
func Copy(src, dst string) error {

  data, err := ioutil.ReadFile(src)
  if err != nil {
    return err
  }

  err = ioutil.WriteFile(dst, data, 0644)
  if err != nil {
    return err
  }

  return nil
}

func main() {
  Copy("access.log", "access.1.log")
}