前言

慢慢增加。。。

os.Stat(path)

函数原型：

// Stat returns a FileInfo describing the named file.
// If there is an error, it will be of type *PathError.
func Stat(name string) (FileInfo, error) {
	testlog.Stat(name)
	return statNolog(name)
}

描述：
Stat返回描述命名文件的FileInfo。如果有错误，则类型为*PathError。

os.IsNotExist(err)

函数原型：

// IsNotExist returns a boolean indicating whether the error is known to
// report that a file or directory does not exist. It is satisfied by
// ErrNotExist as well as some syscall errors.
//
// This function predates errors.Is. It only supports errors returned by
// the os package. New code should use errors.Is(err, os.ErrNotExist).
func IsNotExist(err error) bool {
	return underlyingErrorIs(err, ErrNotExist)
}

描述：
IsNotExist返回一个布尔值，指示是否已知报告文件或目录不存在的错误。ErrNotExist以及一些系统调用错误都满足了这一要求。

此函数早于errors.Is。它只支持操作系统包返回的错误。新代码应该使用errors.Is（err，os.ErrNotExist）。

os.Mkdir()

函数原型：

// Mkdir creates a new directory with the specified name and permission
// bits (before umask).
// If there is an error, it will be of type *PathError.
func Mkdir(name string, perm FileMode) error {
	if runtime.GOOS == "windows" && isWindowsNulName(name) {
		return &PathError{Op: "mkdir", Path: name, Err: syscall.ENOTDIR}
	}
	longName := fixLongPath(name)
	e := ignoringEINTR(func() error {
		return syscall.Mkdir(longName, syscallMode(perm))
	})

	if e != nil {
		return &PathError{Op: "mkdir", Path: name, Err: e}
	}

	// mkdir(2) itself won't handle the sticky bit on *BSD and Solaris
	if !supportsCreateWithStickyBit && perm&ModeSticky != 0 {
		e = setStickyBit(name)

		if e != nil {
			Remove(name)
			return e
		}
	}

	return nil
}