package main import ( "fmt" "os" "golang.org/x/sys/unix" ) func main() { if len(os.Args) != 2 { fmt.Fprintf(os.Stderr, "usage: access \n") os.Exit(1) } filename := os.Args[1] if err := unix.Access(filename, unix.W_OK); err != nil { fmt.Printf("%v: %v\n", filename, err) } }