package main
import (
    "os"
    "fmt"
)
func main() {
    fd, err := os.Open("/var/run/utmpx")
    fmt.Println(fd, err)
    var data []byte
    len, err := fd.Read(data)
    fmt.Println(len, err)
}

<details>
<summary>英文:</summary>
    package main
    import (
     &quot;os&quot;
     &quot;fmt&quot;
    )
    func main() {
      fd, err := os.Open(&quot;/var/run/utmpx&quot;)
      fmt.Println(fd, err)
      var data []byte
      len, err := fd.Read(data)
      fmt.Println(len, err)
    }
&gt; &amp;{0xc42000a240} nil
&gt; 0 nil
There is no error, also no data.
This path `/var/run/utmpx` is read from system header file. 
How to get this path is [another question][1]
system: macOS el capiton, go version go1.8 darwin/amd64
**My final goal is to read this file into go struct.**This file contains system users infomation.
**Can I do that ?** I will keep trying...
  [1]: https://stackoverflow.com/q/44036358/5819540
</details>
# 答案1
**得分**: 2
你可以使用`ioutil.ReadFile`函数来实现：
```go
package main
import (
	"fmt"
	"io/ioutil"
)
func main() {
	fd, err := ioutil.ReadFile("/var/run/utmpx")
	fmt.Println(string(fd), err)
}