正如在其他回答中提到的，可以通过使用os.OpenFile的不同标志来构造所需的行为/错误。事实上，os。Create只是这样做的一个合理的默认值简写:

// Create creates or truncates the named file. If the file already exists,
// it is truncated. If the file does not exist, it is created with mode 0666
// (before umask). If successful, methods on the returned File can
// be used for I/O; the associated file descriptor has mode O_RDWR.
// If there is an error, it will be of type *PathError.
func Create(name string) (*File, error) {
    return OpenFile(name, O_RDWR|O_CREATE|O_TRUNC, 0666)
}

你应该自己结合这些标志来获得你感兴趣的行为:

// Flags to OpenFile wrapping those of the underlying system. Not all
// flags may be implemented on a given system.
const (
    // Exactly one of O_RDONLY, O_WRONLY, or O_RDWR must be specified.
    O_RDONLY int = syscall.O_RDONLY // open the file read-only.
    O_WRONLY int = syscall.O_WRONLY // open the file write-only.
    O_RDWR   int = syscall.O_RDWR   // open the file read-write.
    // The remaining values may be or'ed in to control behavior.
    O_APPEND int = syscall.O_APPEND // append data to the file when writing.
    O_CREATE int = syscall.O_CREAT  // create a new file if none exists.
    O_EXCL   int = syscall.O_EXCL   // used with O_CREATE, file must not exist.
    O_SYNC   int = syscall.O_SYNC   // open for synchronous I/O.
    O_TRUNC  int = syscall.O_TRUNC  // truncate regular writable file when opened.
)

根据您选择的内容，您将得到不同的错误。

下面是一个示例，它将截断一个现有文件，或者当文件存在时失败。

openOpts := os.O_RDWR|os.O_CREATE
if truncateWhenExists {
    openOpts |= os.O_TRUNC // file will be truncated
} else {
    openOpts |= os.O_EXCL  // file must not exist
}
f, err := os.OpenFile(filePath, openOpts, 0644)
// ... do stuff

检查一个文件是否不存在，相当于Python的if not os.path.exists(filename):

if _, err := os.Stat("/path/to/whatever"); errors.Is(err, os.ErrNotExist) {
  // path/to/whatever does not exist
}

检查一个文件是否存在，相当于Python的if os.path.exists(filename):

编辑:根据最近的评论

if _, err := os.Stat("/path/to/whatever"); err == nil {
  // path/to/whatever exists

} else if errors.Is(err, os.ErrNotExist) {
  // path/to/whatever does *not* exist

} else {
  // Schrodinger: file may or may not exist. See err for details.

  // Therefore, do *NOT* use !os.IsNotExist(err) to test for file existence


}

正如在其他回答中提到的，可以通过使用os.OpenFile的不同标志来构造所需的行为/错误。事实上，os。Create只是这样做的一个合理的默认值简写:

// Create creates or truncates the named file. If the file already exists,
// it is truncated. If the file does not exist, it is created with mode 0666
// (before umask). If successful, methods on the returned File can
// be used for I/O; the associated file descriptor has mode O_RDWR.
// If there is an error, it will be of type *PathError.
func Create(name string) (*File, error) {
    return OpenFile(name, O_RDWR|O_CREATE|O_TRUNC, 0666)
}

你应该自己结合这些标志来获得你感兴趣的行为:

// Flags to OpenFile wrapping those of the underlying system. Not all
// flags may be implemented on a given system.
const (
    // Exactly one of O_RDONLY, O_WRONLY, or O_RDWR must be specified.
    O_RDONLY int = syscall.O_RDONLY // open the file read-only.
    O_WRONLY int = syscall.O_WRONLY // open the file write-only.
    O_RDWR   int = syscall.O_RDWR   // open the file read-write.
    // The remaining values may be or'ed in to control behavior.
    O_APPEND int = syscall.O_APPEND // append data to the file when writing.
    O_CREATE int = syscall.O_CREAT  // create a new file if none exists.
    O_EXCL   int = syscall.O_EXCL   // used with O_CREATE, file must not exist.
    O_SYNC   int = syscall.O_SYNC   // open for synchronous I/O.
    O_TRUNC  int = syscall.O_TRUNC  // truncate regular writable file when opened.
)

根据您选择的内容，您将得到不同的错误。

下面是一个示例，它将截断一个现有文件，或者当文件存在时失败。

openOpts := os.O_RDWR|os.O_CREATE
if truncateWhenExists {
    openOpts |= os.O_TRUNC // file will be truncated
} else {
    openOpts |= os.O_EXCL  // file must not exist
}
f, err := os.OpenFile(filePath, openOpts, 0644)
// ... do stuff

    _, err := os.Stat(file)
    if err == nil {
        log.Printf("file %s exists", file)
    } else if os.IsNotExist(err) {
        log.Printf("file %s not exists", file)
    } else {
        log.Printf("file %s stat error: %v", file, err)
    }

你应该使用os.Stat()和os.IsNotExist()函数，如下例所示:

func Exists(name string) (bool, error) {
    _, err := os.Stat(name)
    if err == nil {
        return true, nil
    }
    if errors.Is(err, os.ErrNotExist) {
        return false, nil
    }
    return false, err
}

修正了在某些情况下返回true的问题。 edit2:从os.IsNotExist()切换到使用errors.Is()，许多人说这是最佳实践

答案由Caleb Spare张贴在gonuts邮件列表中。

[...] It's not actually needed very often and [...] using os.Stat is easy enough for the cases where it is required. [...] For instance: if you are going to open the file, there's no reason to check whether it exists first. The file could disappear in between checking and opening, and anyway you'll need to check the os.Open error regardless. So you simply call os.IsNotExist(err) after you try to open the file, and deal with its non-existence there (if that requires special handling). [...] You don't need to check for the paths existing at all (and you shouldn't). os.MkdirAll works whether or not the paths already exist. (Also you need to check the error from that call.) Instead of using os.Create, you should use os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0666) . That way you'll get an error if the file already exists. Also this doesn't have a race condition with something else making the file, unlike your version which checks for existence beforehand.

摘自:https://groups.google.com/forum/#!味精rl8ffhr8v4j / golang-nuts / Ayx-BMNdMFo / 4