operating

type ReadCloserAt interface {
	io.ReadCloser
	io.ReaderAt
}

type SystemFunctions struct {
	Chmod         func(name string, mode os.FileMode) error
	CurrentUser   func() (*user.User, error)
	Getenv        func(key string) string
	Getpid        func() int
	Glob          func(pattern string) (matches []string, err error)
	Hostname      func() (string, error)
	IsNotExist    func(err error) bool
	MkdirAll      func(path string, perm os.FileMode) error
	Now           func() time.Time
	OpenFileRead  func(name string, flag int, perm os.FileMode) (ReadCloserAt, error)
	OpenFileWrite func(name string, flag int, perm os.FileMode) (io.WriteCloser, error)
	ReadFile      func(filename string) ([]byte, error)
	Remove        func(name string) error
	RemoveAll     func(name string) error
	Stat          func(name string) (os.FileInfo, error)
	Stdin         ReadCloserAt
	Stdout        io.WriteCloser
	TempFile      func(dir, pattern string) (f *os.File, err error)
	Local         *time.Location
}