How to Get File Length in Go

Created May 6, 2022 at 18:23

Modified May 6, 2022 at 20:02

Using file.Stat Function

Open opens the named file for reading. If successful, methods on the returned file can be used for reading; the associated file descriptor has mode O_RDONLY.

See the following example:

package main

import (
  "fmt"
  "os"
)

func main() {
  f, err := os.Open("access.log")
  if err != nil {
    // log.Fatal(err)
  }
  defer f.Close()

  stat, _ := f.Stat()
  fmt.Println(stat.Size())
  // fmt.Println(FormatByteSI(stat.Size()))
}

2626
2.6 kB

Using os.Stat Function

If you don't want to open the file, you can directly call os.Stat instead.

For example,

package main

import (
  "fmt"
  "os"
)

func main() {

  stat, err := os.Stat("access.log")
  if err != nil {
    // log.Fatal(err)
  }
  fmt.Println(stat.Size())
  // fmt.Println(FormatByteSI(stat.Size()))
}