检查文件是否不存在,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
}
< p >[…实际上并不经常需要,而且[…]使用os.Stat是
对于需要它的情况来说很简单。< / p >
< p >[…例如:如果你要打开文件,没有理由先检查它是否存在。文件可能会在检查和打开之间消失,无论如何您都需要检查os.Open错误。因此,您只需在尝试后调用os.IsNotExist(err)
打开文件,并处理它不存在的问题(如果需要特殊处理的话)。< / p >
// 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