package main

import (  
    "fmt"
    "os"
)

func main() {  
    f, err := os.Open("/test.txt")
    err, ok := err.(*os.PathError);
    if  ok {
        fmt.Println("File at path", err.Path, "failed to open")
        return
    }
    fmt.Println(f.Name(), "opened successfully")
}

这样写报错：# command-line-arguments
usercode/file.go:12: err.Path undefined (type error has no field or method Path)
把加粗的err换成别的，比如err2，可以正常输出
但是如下写法，没问题：
package main

import (  
    "fmt"
    "os"
)

func main() {  
    f, err := os.Open("/test.txt")
    if err, ok := err.(*os.PathError); ok {
        fmt.Println("File at path", err.Path, "failed to open")
        return
    }
    fmt.Println(f.Name(), "opened successfully")
}
--
FROM 120.242.252.*