操作系统接口
os模块提供了许多与操作系统交互的函数
import os
os.getcwd() # Return the current working directory'C:\\Users\\way'
os.chdir('C:\\Users\\way\\desktop') # Change current working directryos.system('mkdir today') # Run the command mkdir in the system shell0
确保使用import os而不是from os import *。这会防止内置函数open()比os.open优先调用，引起不同的操作。
内置的dir()和help()函数有利于操作大的模块如os时的交互辅助。
import os
dir(os)['F_OK',
'MutableMapping',
'O_APPEND',
'O_BINARY',
'O_CREAT',
'O_EXCL',
'O_NOINHERIT',
'O_RANDOM',
'O_RDONLY',
'O_RDWR',
'O_SEQUENTIAL',
'O_SHORT_LIVED',
'O_TEMPORARY',
'O_TEXT',
'O_TRUNC',
'O_WRONLY',
'P_DETACH',
'P_NOWAIT',
'P_NOWAITO',
'P_OVERLAY',
'P_WAIT',
'R_OK',
'SEEK_CUR',
'SEEK_END',
'SEEK_SET',
'TMP_MAX',
'W_OK',
'X_OK',
'_Environ',
'__all__',
'__builtins__',
'__cached__',
'__doc__',
'__file__',
'__loader__',
'__name__',
'__package__',
'__spec__',
'_execvpe',
'_exists',
'_exit',
'_get_exports_list',
'_putenv',
'_unsetenv',
'_wrap_close',
'abort',
'access',
'altsep',
'chdir',
'chmod',
'close',
'closerange',
'cpu_count',
'curdir',
'defpath',
'device_encoding',
'devnull',
'dup',
'dup2',
'environ',
'errno',
'error',
'execl',
'execle',
'execlp',
'execlpe',
'execv',
'execve',
'execvp',
'execvpe',
'extsep',
'fdopen',
'fsdecode',
'fsencode',
'fstat',
'fsync',
'get_exec_path',
'get_handle_inheritable',
'get_inheritable',
'get_terminal_size',
'getcwd',
'getcwdb',
'getenv',
'getlogin',
'getpid',
'getppid',
'isatty',
'kill',
'linesep',
'link',
'listdir',
'lseek',
'lstat',
'makedirs',
'mkdir',
'name',
'open',
'pardir',
'path',
'pathsep',
'pipe',
'popen',
'putenv',
'read',
'readlink',
'remove',
'removedirs',
'rename',
'renames',
'replace',
'rmdir',
'sep',
'set_handle_inheritable',
'set_inheritable',
'spawnl',
'spawnle',
'spawnv',
'spawnve',
'st',
'startfile',
'stat',
'stat_float_times',
'stat_result',
'statvfs_result',
'strerror',
'supports_bytes_environ',
'supports_dir_fd',
'supports_effective_ids',
'supports_fd',
'supports_follow_symlinks',
'symlink',
'sys',
'system',
'terminal_size',
'times',
'times_result',
'umask',
'uname_result',
'unlink',
'urandom',
'utime',
'waitpid',
'walk',
'write']
help(os)Help on module os:
NAME
os - OS routines for NT or Posix depending on what system we're on.
DESCRIPTION
This exports:
- all functions from posix, nt or ce, e.g. unlink, stat, etc.
- os.path is either posixpath or ntpath
- os.name is either 'posix', 'nt' or 'ce'.
- os.curdir is a string representing the current directory ('.' or ':')
- os.pardir is a string representing the parent directory ('..' or '::')
- os.sep is the (or a most common) pathname separator ('/' or ':' or '\\')
- os.extsep is the extension separator (always '.')
- os.altsep is the alternate pathname separator (None or '/')
- os.pathsep is the component separator used in $PATH etc
- os.linesep is the line separator in text files ('\r' or '\n' or '\r\n')
- os.defpath is the default search path for executables
- os.devnull is the file path of the null device ('/dev/null', etc.)
Programs that import and use 'os' stand a better chance of being
portable between different platforms. Of course, they must then
only use functions that are defined by all platforms (e.g., unlink
and opendir), and leave all pathname manipulation to os.path
(e.g., split and join).
CLASSES
builtins.Exception(builtins.BaseException)
builtins.OSError
builtins.tuple(builtins.object)
nt.times_result
nt.uname_result
stat_result
statvfs_result
terminal_size
error = class OSError(Exception)
| Base class for I/O related errors.
|
| Method resolution order:
| OSError
| Exception
| BaseException
| object
|
| Methods defined here:
|
| __init__(self, /, *args, **kwargs)
| Initialize self. See help(type(self)) for accurate signature.
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| __reduce__(...)
|
| __str__(self, /)
| Return str(self).
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| characters_written
|
| errno
| POSIX exception code
|
| filename
| exception filename
|
| filename2
| second exception filename
|
| strerror
| exception strerror
|
| winerror
| Win32 exception code
|
| ----------------------------------------------------------------------
| Methods inherited from BaseException:
|
| __delattr__(self, name, /)
| Implement delattr(self, name).
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __repr__(self, /)
| Return repr(self).
|
| __setattr__(self, name, value, /)
| Implement setattr(self, name, value).
|
| __setstate__(...)
|
| with_traceback(...)
| Exception.with_traceback(tb) --
| set self.__traceback__ to tb and return self.
|
| ----------------------------------------------------------------------
| Data descriptors inherited from BaseException:
|
| __cause__
| exception cause
|
| __context__
| exception context
|
| __dict__
|
| __suppress_context__
|
| __traceback__
|
| args
class stat_result(builtins.tuple)
| stat_result: Result from stat, fstat, or lstat.
|
| This object may be accessed either as a tuple of
| (mode, ino, dev, nlink, uid, gid, size, atime, mtime, ctime)
| or via the attributes st_mode, st_ino, st_dev, st_nlink, st_uid, and so on.
|
| Posix/windows: If your platform supports st_blksize, st_blocks, st_rdev,
| or st_flags, they are available as attributes only.
|
| See os.stat for more information.
|
| Method resolution order:
| stat_result
| builtins.tuple
| builtins.object
|
| Methods defined here:
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| __reduce__(...)
|
| __repr__(self, /)
| Return repr(self).
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| st_atime
| time of last access
|
| st_atime_ns
| time of last access in nanoseconds
|
| st_ctime
| time of last change
|
| st_ctime_ns
| time of last change in nanoseconds
|
| st_dev
| device
|
| st_gid
| group ID of owner
|
| st_ino
| inode
|
| st_mode
| protection bits
|
| st_mtime
| time of last modification
|
| st_mtime_ns
| time of last modification in nanoseconds
|
| st_nlink
| number of hard links
|
| st_size
| total size, in bytes
|
| st_uid
| user ID of owner
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| n_fields = 16
|
| n_sequence_fields = 10
|
| n_unnamed_fields = 3
|
| ----------------------------------------------------------------------
| Methods inherited from builtins.tuple:
|
| __add__(self, value, /)
| Return self+value.
|
| __contains__(self, key, /)
| Return key in self.
|
| __eq__(self, value, /)
| Return self==value.
|
| __ge__(self, value, /)
| Return self>=value.
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __getitem__(self, key, /)
| Return self[key].
|
| __getnewargs__(...)
|
| __gt__(self, value, /)
| Return self>value.
|
| __hash__(self, /)
| Return hash(self).
|
| __iter__(self, /)
| Implement iter(self).
|
| __le__(self, value, /)
| Return self<=value.
|
| __len__(self, /)
| Return len(self).
|
| __lt__(self, value, /)
| Return self<value.
|
| __mul__(self, value, /)
| Return self*value.n
|
| __ne__(self, value, /)
| Return self!=value.
|
| __rmul__(self, value, /)
| Return self*value.
|
| count(...)
| T.count(value) -> integer -- return number of occurrences of value
|
| index(...)
| T.index(value, [start, [stop]]) -> integer -- return first index of value.
| Raises ValueError if the value is not present.
class statvfs_result(builtins.tuple)
| statvfs_result: Result from statvfs or fstatvfs.
|
| This object may be accessed either as a tuple of
| (bsize, frsize, blocks, bfree, bavail, files, ffree, favail, flag, namemax),
| or via the attributes f_bsize, f_frsize, f_blocks, f_bfree, and so on.
|
| See os.statvfs for more information.
|
| Method resolution order:
| statvfs_result
| builtins.tuple
| builtins.object
|
| Methods defined here:
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| __reduce__(...)
|
| __repr__(self, /)
| Return repr(self).
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| f_bavail
|
| f_bfree
|
| f_blocks
|
| f_bsize
|
| f_favail
|
| f_ffree
|
| f_files
|
| f_flag
|
| f_frsize
|
| f_namemax
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| n_fields = 10
|
| n_sequence_fields = 10
|
| n_unnamed_fields = 0
|
| ----------------------------------------------------------------------
| Methods inherited from builtins.tuple:
|
| __add__(self, value, /)
| Return self+value.
|
| __contains__(self, key, /)
| Return key in self.
|
| __eq__(self, value, /)
| Return self==value.
|
| __ge__(self, value, /)
| Return self>=value.
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __getitem__(self, key, /)
| Return self[key].
|
| __getnewargs__(...)
|
| __gt__(self, value, /)
| Return self>value.
|
| __hash__(self, /)
| Return hash(self).
|
| __iter__(self, /)
| Implement iter(self).
|
| __le__(self, value, /)
| Return self<=value.
|
| __len__(self, /)
| Return len(self).
|
| __lt__(self, value, /)
| Return self<value.
|
| __mul__(self, value, /)
| Return self*value.n
|
| __ne__(self, value, /)
| Return self!=value.
|
| __rmul__(self, value, /)
| Return self*value.
|
| count(...)
| T.count(value) -> integer -- return number of occurrences of value
|
| index(...)
| T.index(value, [start, [stop]]) -> integer -- return first index of value.
| Raises ValueError if the value is not present.
class terminal_size(builtins.tuple)
| A tuple of (columns, lines) for holding terminal window size
|
| Method resolution order:
| terminal_size
| builtins.tuple
| builtins.object
|
| Methods defined here:
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| __reduce__(...)
|
| __repr__(self, /)
| Return repr(self).
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| columns
| width of the terminal window in characters
|
| lines
| height of the terminal window in characters
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| n_fields = 2
|
| n_sequence_fields = 2
|
| n_unnamed_fields = 0
|
| ----------------------------------------------------------------------
| Methods inherited from builtins.tuple:
|
| __add__(self, value, /)
| Return self+value.
|
| __contains__(self, key, /)
| Return key in self.
|
| __eq__(self, value, /)
| Return self==value.
|
| __ge__(self, value, /)
| Return self>=value.
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __getitem__(self, key, /)
| Return self[key].
|
| __getnewargs__(...)
|
| __gt__(self, value, /)
| Return self>value.
|
| __hash__(self, /)
| Return hash(self).
|
| __iter__(self, /)
| Implement iter(self).
|
| __le__(self, value, /)
| Return self<=value.
|
| __len__(self, /)
| Return len(self).
|
| __lt__(self, value, /)
| Return self<value.
|
| __mul__(self, value, /)
| Return self*value.n
|
| __ne__(self, value, /)
| Return self!=value.
|
| __rmul__(self, value, /)
| Return self*value.
|
| count(...)
| T.count(value) -> integer -- return number of occurrences of value
|
| index(...)
| T.index(value, [start, [stop]]) -> integer -- return first index of value.
| Raises ValueError if the value is not present.
class times_result(builtins.tuple)
| times_result: Result from os.times().
|
| This object may be accessed either as a tuple of
| (user, system, children_user, children_system, elapsed),
| or via the attributes user, system, children_user, children_system,
| and elapsed.
|
| See os.times for more information.
|
| Method resolution order:
| times_result
| builtins.tuple
| builtins.object
|
| Methods defined here:
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| __reduce__(...)
|
| __repr__(self, /)
| Return repr(self).
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| children_system
| system time of children
|
| children_user
| user time of children
|
| elapsed
| elapsed time since an arbitrary point in the past
|
| system
| system time
|
| user
| user time
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| n_fields = 5
|
| n_sequence_fields = 5
|
| n_unnamed_fields = 0
|
| ----------------------------------------------------------------------
| Methods inherited from builtins.tuple:
|
| __add__(self, value, /)
| Return self+value.
|
| __contains__(self, key, /)
| Return key in self.
|
| __eq__(self, value, /)
| Return self==value.
|
| __ge__(self, value, /)
| Return self>=value.
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __getitem__(self, key, /)
| Return self[key].
|
| __getnewargs__(...)
|
| __gt__(self, value, /)
| Return self>value.
|
| __hash__(self, /)
| Return hash(self).
|
| __iter__(self, /)
| Implement iter(self).
|
| __le__(self, value, /)
| Return self<=value.
|
| __len__(self, /)
| Return len(self).
|
| __lt__(self, value, /)
| Return self<value.
|
| __mul__(self, value, /)
| Return self*value.n
|
| __ne__(self, value, /)
| Return self!=value.
|
| __rmul__(self, value, /)
| Return self*value.
|
| count(...)
| T.count(value) -> integer -- return number of occurrences of value
|
| index(...)
| T.index(value, [start, [stop]]) -> integer -- return first index of value.
| Raises ValueError if the value is not present.
class uname_result(builtins.tuple)
| uname_result: Result from os.uname().
|
| This object may be accessed either as a tuple of
| (sysname, nodename, release, version, machine),
| or via the attributes sysname, nodename, release, version, and machine.
|
| See os.uname for more information.
|
| Method resolution order:
| uname_result
| builtins.tuple
| builtins.object
|
| Methods defined here:
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| __reduce__(...)
|
| __repr__(self, /)
| Return repr(self).
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| machine
| hardware identifier
|
| nodename
| name of machine on network (implementation-defined)
|
| release
| operating system release
|
| sysname
| operating system name
|
| version
| operating system version
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| n_fields = 5
|
| n_sequence_fields = 5
|
| n_unnamed_fields = 0
|
| ----------------------------------------------------------------------
| Methods inherited from builtins.tuple:
|
| __add__(self, value, /)
| Return self+value.
|
| __contains__(self, key, /)
| Return key in self.
|
| __eq__(self, value, /)
| Return self==value.
|
| __ge__(self, value, /)
| Return self>=value.
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __getitem__(self, key, /)
| Return self[key].
|
| __getnewargs__(...)
|
| __gt__(self, value, /)
| Return self>value.
|
| __hash__(self, /)
| Return hash(self).
|
| __iter__(self, /)
| Implement iter(self).
|
| __le__(self, value, /)
| Return self<=value.
|
| __len__(self, /)
| Return len(self).
|
| __lt__(self, value, /)
| Return self<value.
|
| __mul__(self, value, /)
| Return self*value.n
|
| __ne__(self, value, /)
| Return self!=value.
|
| __rmul__(self, value, /)
| Return self*value.
|
| count(...)
| T.count(value) -> integer -- return number of occurrences of value
|
| index(...)
| T.index(value, [start, [stop]]) -> integer -- return first index of value.
| Raises ValueError if the value is not present.
FUNCTIONS
_exit(...)
_exit(status)
Exit to the system with specified status, without normal exit processing.
abort(...)
abort() -> does not return!
Abort the interpreter immediately. This 'dumps core' or otherwise fails
in the hardest way possible on the hosting operating system.
access(path, mode, *, dir_fd=None, effective_ids=False, follow_symlinks=True)
Use the real uid/gid to test for access to a path.
path
Path to be tested; can be string, bytes, or open-file-descriptor int.
mode
Operating-system mode bitfield. Can be F_OK to test existence,
or the inclusive-OR of R_OK, W_OK, and X_OK.
dir_fd
If not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that
directory.
effective_ids
If True, access will use the effective uid/gid instead of
the real uid/gid.
follow_symlinks
If False, and the last element of the path is a symbolic link,
access will examine the symbolic link itself instead of the file
the link points to.
dir_fd, effective_ids, and follow_symlinks may not be implemented
on your platform. If they are unavailable, using them will raise a
NotImplementedError.
Note that most operations will use the effective uid/gid, therefore this
routine can be used in a suid/sgid environment to test if the invoking user
has the specified access to the path.
chdir(...)
chdir(path)
Change the current working directory to the specified path.
path may always be specified as a string.
On some platforms, path may also be specified as an open file descriptor.
If this functionality is unavailable, using it raises an exception.
chmod(...)
chmod(path, mode, *, dir_fd=None, follow_symlinks=True)
Change the access permissions of a file.
path may always be specified as a string.
On some platforms, path may also be specified as an open file descriptor.
If this functionality is unavailable, using it raises an exception.
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
If follow_symlinks is False, and the last element of the path is a symbolic
link, chmod will modify the symbolic link itself instead of the file the
link points to.
It is an error to use dir_fd or follow_symlinks when specifying path as
an open file descriptor.
dir_fd and follow_symlinks may not be implemented on your platform.
If they are unavailable, using them will raise a NotImplementedError.
close(...)
close(fd)
Close a file descriptor (for low level IO).
closerange(...)
closerange(fd_low, fd_high)
Closes all file descriptors in [fd_low, fd_high), ignoring errors.
cpu_count(...)
cpu_count() -> integer
Return the number of CPUs in the system, or None if this value cannot be
established.
device_encoding(...)
device_encoding(fd) -> str
Return a string describing the encoding of the device
if the output is a terminal; else return None.
dup(...)
dup(fd) -> fd2
Return a duplicate of a file descriptor.
dup2(...)
dup2(old_fd, new_fd)
Duplicate file descriptor.
execl(file, *args)
execl(file, *args)
Execute the executable file with argument list args, replacing the
current process.
execle(file, *args)
execle(file, *args, env)
Execute the executable file with argument list args and
environment env, replacing the current process.
execlp(file, *args)
execlp(file, *args)
Execute the executable file (which is searched for along $PATH)
with argument list args, replacing the current process.
execlpe(file, *args)
execlpe(file, *args, env)
Execute the executable file (which is searched for along $PATH)
with argument list args and environment env, replacing the current
process.
execv(...)
execv(path, args)
Execute an executable path with arguments, replacing current process.
path: path of executable file
args: tuple or list of strings
execve(...)
execve(path, args, env)
Execute a path with arguments and environment, replacing current process.
path: path of executable file
args: tuple or list of arguments
env: dictionary of strings mapping to strings
On some platforms, you may specify an open file descriptor for path;
execve will execute the program the file descriptor is open to.
If this functionality is unavailable, using it raises NotImplementedError.
execvp(file, args)
execvp(file, args)
Execute the executable file (which is searched for along $PATH)
with argument list args, replacing the current process.
args may be a list or tuple of strings.
execvpe(file, args, env)
execvpe(file, args, env)
Execute the executable file (which is searched for along $PATH)
with argument list args and environment env , replacing the
current process.
args may be a list or tuple of strings.
fdopen(fd, *args, **kwargs)
# Supply os.fdopen()
fsdecode(filename)
Decode filename from the filesystem encoding with 'surrogateescape' error
handler, return str unchanged. On Windows, use 'strict' error handler if
the file system encoding is 'mbcs' (which is the default encoding).
fsencode(filename)
Encode filename to the filesystem encoding with 'surrogateescape' error
handler, return bytes unchanged. On Windows, use 'strict' error handler if
the file system encoding is 'mbcs' (which is the default encoding).
fstat(...)
fstat(fd) -> stat result
Like stat(), but for an open file descriptor.
Equivalent to stat(fd=fd).
fsync(...)
fsync(fildes)
force write of file with filedescriptor to disk.
get_exec_path(env=None)
Returns the sequence of directories that will be searched for the
named executable (similar to a shell) when launching a process.
*env* must be an environment variable dict or None. If *env* is None,
os.environ will be used.
get_handle_inheritable(...)
get_handle_inheritable(fd) -> bool
Get the close-on-exe flag of the specified file descriptor.
get_inheritable(...)
get_inheritable(fd) -> bool
Get the close-on-exe flag of the specified file descriptor.
get_terminal_size(...)
Return the size of the terminal window as (columns, lines).
The optional argument fd (default standard output) specifies
which file descriptor should be queried.
If the file descriptor is not connected to a terminal, an OSError
is thrown.
This function will only be defined if an implementation is
available for this system.
shutil.get_terminal_size is the high-level function which should
normally be used, os.get_terminal_size is the low-level implementation.
getcwd(...)
getcwd() -> path
Return a unicode string representing the current working directory.
getcwdb(...)
getcwdb() -> path
Return a bytes string representing the current working directory.
getenv(key, default=None)
Get an environment variable, return None if it doesn't exist.
The optional second argument can specify an alternate default.
key, default and the result are str.
getlogin(...)
getlogin() -> string
Return the actual login name.
getpid(...)
getpid() -> pid
Return the current process id
getppid(...)
getppid() -> ppid
Return the parent's process id. If the parent process has already exited,
Windows machines will still return its id; others systems will return the id
of the 'init' process (1).
isatty(...)
isatty(fd) -> bool
Return True if the file descriptor 'fd' is an open file descriptor
connected to the slave end of a terminal.
kill(...)
kill(pid, sig)
Kill a process with a signal.
link(...)
link(src, dst, *, src_dir_fd=None, dst_dir_fd=None, follow_symlinks=True)
Create a hard link to a file.
If either src_dir_fd or dst_dir_fd is not None, it should be a file
descriptor open to a directory, and the respective path string (src or dst)
should be relative; the path will then be relative to that directory.
If follow_symlinks is False, and the last element of src is a symbolic
link, link will create a link to the symbolic link itself instead of the
file the link points to.
src_dir_fd, dst_dir_fd, and follow_symlinks may not be implemented on your
platform. If they are unavailable, using them will raise a
NotImplementedError.
listdir(...)
listdir(path='.') -> list_of_filenames
Return a list containing the names of the files in the directory.
The list is in arbitrary order. It does not include the special
entries '.' and '..' even if they are present in the directory.
path can be specified as either str or bytes. If path is bytes,
the filenames returned will also be bytes; in all other circumstances
the filenames returned will be str.
On some platforms, path may also be specified as an open file descriptor;
the file descriptor must refer to a directory.
If this functionality is unavailable, using it raises NotImplementedError.
lseek(...)
lseek(fd, pos, how) -> newpos
Set the current position of a file descriptor.
Return the new cursor position in bytes, starting from the beginning.
lstat(...)
lstat(path, *, dir_fd=None) -> stat result
Like stat(), but do not follow symbolic links.
Equivalent to stat(path, follow_symlinks=False).
makedirs(name, mode=511, exist_ok=False)
makedirs(name [, mode=0o777][, exist_ok=False])
Super-mkdir; create a leaf directory and all intermediate ones. Works like
mkdir, except that any intermediate path segment (not just the rightmost)
will be created if it does not exist. If the target directory already
exists, raise an OSError if exist_ok is False. Otherwise no exception is
raised. This is recursive.
mkdir(...)
mkdir(path, mode=0o777, *, dir_fd=None)
Create a directory.
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
dir_fd may not be implemented on your platform.
If it is unavailable, using it will raise a NotImplementedError.
The mode argument is ignored on Windows.
open(...)
open(path, flags, mode=0o777, *, dir_fd=None)
Open a file for low level IO. Returns a file handle (integer).
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
dir_fd may not be implemented on your platform.
If it is unavailable, using it will raise a NotImplementedError.
pipe(...)
pipe() -> (read_end, write_end)
Create a pipe.
popen(cmd, mode='r', buffering=-1)
# Supply os.popen()
putenv(...)
putenv(key, value)
Change or add an environment variable.
read(...)
read(fd, buffersize) -> bytes
Read a file descriptor.
readlink(...)
readlink(path, *, dir_fd=None) -> path
Return a string representing the path to which the symbolic link points.
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
dir_fd may not be implemented on your platform.
If it is unavailable, using it will raise a NotImplementedError.
remove(...)
remove(path, *, dir_fd=None)
Remove a file (same as unlink()).
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
dir_fd may not be implemented on your platform.
If it is unavailable, using it will raise a NotImplementedError.
removedirs(name)
removedirs(name)
Super-rmdir; remove a leaf directory and all empty intermediate
ones. Works like rmdir except that, if the leaf directory is
successfully removed, directories corresponding to rightmost path
segments will be pruned away until either the whole path is
consumed or an error occurs. Errors during this latter phase are
ignored -- they generally mean that a directory was not empty.
rename(...)
rename(src, dst, *, src_dir_fd=None, dst_dir_fd=None)
Rename a file or directory.
If either src_dir_fd or dst_dir_fd is not None, it should be a file
descriptor open to a directory, and the respective path string (src or dst)
should be relative; the path will then be relative to that directory.
src_dir_fd and dst_dir_fd, may not be implemented on your platform.
If they are unavailable, using them will raise a NotImplementedError.
renames(old, new)
renames(old, new)
Super-rename; create directories as necessary and delete any left
empty. Works like rename, except creation of any intermediate
directories needed to make the new pathname good is attempted
first. After the rename, directories corresponding to rightmost
path segments of the old name will be pruned until either the
whole path is consumed or a nonempty directory is found.
Note: this function can fail with the new directory structure made
if you lack permissions needed to unlink the leaf directory or
file.
replace(...)
replace(src, dst, *, src_dir_fd=None, dst_dir_fd=None)
Rename a file or directory, overwriting the destination.
If either src_dir_fd or dst_dir_fd is not None, it should be a file
descriptor open to a directory, and the respective path string (src or dst)
should be relative; the path will then be relative to that directory.
src_dir_fd and dst_dir_fd, may not be implemented on your platform.
If they are unavailable, using them will raise a NotImplementedError.
rmdir(...)
rmdir(path, *, dir_fd=None)
Remove a directory.
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
dir_fd may not be implemented on your platform.
If it is unavailable, using it will raise a NotImplementedError.
set_handle_inheritable(...)
set_handle_inheritable(fd, inheritable)
Set the inheritable flag of the specified handle.
set_inheritable(...)
set_inheritable(fd, inheritable)
Set the inheritable flag of the specified file descriptor.
spawnl(mode, file, *args)
spawnl(mode, file, *args) -> integer
Execute file with arguments from args in a subprocess.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it.
spawnle(mode, file, *args)
spawnle(mode, file, *args, env) -> integer
Execute file with arguments from args in a subprocess with the
supplied environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it.
spawnv(...)
spawnv(mode, path, args)
Execute the program 'path' in a new process.
mode: mode of process creation
path: path of executable file
args: tuple or list of strings
spawnve(...)
spawnve(mode, path, args, env)
Execute the program 'path' in a new process.
mode: mode of process creation
path: path of executable file
args: tuple or list of arguments
env: dictionary of strings mapping to strings
startfile(...)
startfile(filepath [, operation]) - Start a file with its associated
application.
When "operation" is not specified or "open", this acts like
double-clicking the file in Explorer, or giving the file name as an
argument to the DOS "start" command: the file is opened with whatever
application (if any) its extension is associated.
When another "operation" is given, it specifies what should be done with
the file. A typical operation is "print".
startfile returns as soon as the associated application is launched.
There is no option to wait for the application to close, and no way
to retrieve the application's exit status.
The filepath is relative to the current directory. If you want to use
an absolute path, make sure the first character is not a slash ("/");
the underlying Win32 ShellExecute function doesn't work if it is.
stat(path, *, dir_fd=None, follow_symlinks=True)
Perform a stat system call on the given path.
path
Path to be examined; can be string, bytes, or open-file-descriptor int.
dir_fd
If not None, it should be a file descriptor open to a directory,
and path should be a relative string; path will then be relative to
that directory.
follow_symlinks
If False, and the last element of the path is a symbolic link,
stat will examine the symbolic link itself instead of the file
the link points to.
dir_fd and follow_symlinks may not be implemented
on your platform. If they are unavailable, using them will raise a
NotImplementedError.
It's an error to use dir_fd or follow_symlinks when specifying path as
an open file descriptor.
stat_float_times(...)
stat_float_times([newval]) -> oldval
Determine whether os.[lf]stat represents time stamps as float objects.
If newval is True, future calls to stat() return floats, if it is False,
future calls return ints.
If newval is omitted, return the current setting.
strerror(...)
strerror(code) -> string
Translate an error code to a message string.
symlink(...)
symlink(src, dst, target_is_directory=False, *, dir_fd=None)
Create a symbolic link pointing to src named dst.
target_is_directory is required on Windows if the target is to be
interpreted as a directory. (On Windows, symlink requires
Windows 6.0 or greater, and raises a NotImplementedError otherwise.)
target_is_directory is ignored on non-Windows platforms.
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
dir_fd may not be implemented on your platform.
If it is unavailable, using it will raise a NotImplementedError.
system(...)
system(command) -> exit_status
Execute the command (a string) in a subshell.
times(...)
times() -> times_result
Return an object containing floating point numbers indicating process
times. The object behaves like a named tuple with these fields:
(utime, stime, cutime, cstime, elapsed_time)
umask(...)
umask(new_mask) -> old_mask
Set the current numeric umask and return the previous umask.
unlink(...)
unlink(path, *, dir_fd=None)
Remove a file (same as remove()).
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
dir_fd may not be implemented on your platform.
If it is unavailable, using it will raise a NotImplementedError.
urandom(...)
urandom(n) -> str
Return n random bytes suitable for cryptographic use.
utime(...)
utime(path, times=None, *[, ns], dir_fd=None, follow_symlinks=True)
Set the access and modified time of path.
path may always be specified as a string.
On some platforms, path may also be specified as an open file descriptor.
If this functionality is unavailable, using it raises an exception.
If times is not None, it must be a tuple (atime, mtime);
atime and mtime should be expressed as float seconds since the epoch.
If ns is specified, it must be a tuple (atime_ns, mtime_ns);
atime_ns and mtime_ns should be expressed as integer nanoseconds
since the epoch.
If times is None and ns is unspecified, utime uses the current time.
Specifying tuples for both times and ns is an error.
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
If follow_symlinks is False, and the last element of the path is a symbolic
link, utime will modify the symbolic link itself instead of the file the
link points to.
It is an error to use dir_fd or follow_symlinks when specifying path
as an open file descriptor.
dir_fd and follow_symlinks may not be available on your platform.
If they are unavailable, using them will raise a NotImplementedError.
waitpid(...)
waitpid(pid, options) -> (pid, status << 8)
Wait for completion of a given process. options is ignored on Windows.
walk(top, topdown=True, onerror=None, followlinks=False)
Directory tree generator.
For each directory in the directory tree rooted at top (including top
itself, but excluding '.' and '..'), yields a 3-tuple
dirpath, dirnames, filenames
dirpath is a string, the path to the directory. dirnames is a list of
the names of the subdirectories in dirpath (excluding '.' and '..').
filenames is a list of the names of the non-directory files in dirpath.
Note that the names in the lists are just names, with no path components.
To get a full path (which begins with top) to a file or directory in
dirpath, do os.path.join(dirpath, name).
If optional arg 'topdown' is true or not specified, the triple for a
directory is generated before the triples for any of its subdirectories
(directories are generated top down). If topdown is false, the triple
for a directory is generated after the triples for all of its
subdirectories (directories are generated bottom up).
When topdown is true, the caller can modify the dirnames list in-place
(e.g., via del or slice assignment), and walk will only recurse into the
subdirectories whose names remain in dirnames; this can be used to prune the
search, or to impose a specific order of visiting. Modifying dirnames when
topdown is false is ineffective, since the directories in dirnames have
already been generated by the time dirnames itself is generated. No matter
the value of topdown, the list of subdirectories is retrieved before the
tuples for the directory and its subdirectories are generated.
By default errors from the os.listdir() call are ignored. If
optional arg 'onerror' is specified, it should be a function; it
will be called with one argument, an OSError instance. It can
report the error to continue with the walk, or raise the exception
to abort the walk. Note that the filename is available as the
filename attribute of the exception object.
By default, os.walk does not follow symbolic links to subdirectories on
systems that support them. In order to get this functionality, set the
optional argument 'followlinks' to true.
Caution: if you pass a relative pathname for top, don't change the
current working directory between resumptions of walk. walk never
changes the current directory, and assumes that the client doesn't
either.
Example:
import os
from os.path import join, getsize
for root, dirs, files in os.walk('python/Lib/email'):
print(root, "consumes", end="")
print(sum([getsize(join(root, name)) for name in files]), end="")
print("bytes in", len(files), "non-directory files")
if 'CVS' in dirs:
dirs.remove('CVS') # don't visit CVS directories
write(...)
write(fd, data) -> byteswritten
Write bytes to a file descriptor.
DATA
F_OK = 0
O_APPEND = 8
O_BINARY = 32768
O_CREAT = 256
O_EXCL = 1024
O_NOINHERIT = 128
O_RANDOM = 16
O_RDONLY = 0
O_RDWR = 2
O_SEQUENTIAL = 32
O_SHORT_LIVED = 4096
O_TEMPORARY = 64
O_TEXT = 16384
O_TRUNC = 512
O_WRONLY = 1
P_DETACH = 4
P_NOWAIT = 1
P_NOWAITO = 3
P_OVERLAY = 2
P_WAIT = 0
R_OK = 4
SEEK_CUR = 1
SEEK_END = 2
SEEK_SET = 0
TMP_MAX = 32767
W_OK = 2
X_OK = 1
__all__ = ['altsep', 'curdir', 'pardir', 'sep', 'pathsep', 'linesep', ...
altsep = '/'
curdir = '.'
defpath = r'.;C:\bin'
devnull = 'nul'
environ = environ({'LOGONSERVER': '\\\\WAY-PC', 'UGII_BASE...ROGRAMFIL...
extsep = '.'
linesep = '\r\n'
name = 'nt'
pardir = '..'
pathsep = ';'
sep = r'\'
supports_bytes_environ = False
FILE
c:\python34\lib\os.py
对于日常文件和目录管理任务，shutil模块提供了易于使用的接口
import shutil
shutil.copyfile('cat2.jpg', 'cat.jpg')'cat.jpg'
shutil.move('cat2.jpg', 'today')'today\\cat2.jpg'
文件通配符file wildcards
glob模块提供了一个功能，可以使用目录通配符搜索生成一个文件列表
import glob
glob.glob('*.py')['batch-rename.py', 'rename.py', 'test.py']
命令行参数
常用的实用程序脚本通常需要处理命令行参数。 这些参数以列表形式存储在sys模块的argv属性中。 例如，下面的输出结果是在命令行运行jupyter notebook的结果：
import sys
print(sys.argv)['C:\\Python34\\lib\\site-packages\\ipykernel_launcher.py', '-f', 'C:\\Users\\way\\AppData\\Roaming\\jupyter\\runtime\\kernel-51225d00-7101-435c-b61c-6430ef69a5b9.json']
getopt模块使用Unix getopt（）函数的约定处理sys.argv。 argparse模块提供更强大，更灵活的命令行处理。
错误输出重定向和程序终止
sys模块还具有stdin，stdout和stderr的属性。 后者可以在即便是stdout被重定向时也可以使警告和错误消息可见：
sys.stderr.write('Warning, log file not found starting a new one\n')Warning, log file not found starting a new one
终止一个脚本最直接的方式是使用sys.exit()
字符串模式匹配（正则表达式）
re模块提供了正则表达式用来高级的字符串处理。对于复杂的匹配和操作，正则表达式提供了简洁高效的方法。
import re
re.findall(r'\bf[a-z]*', 'which foot or hand fell fastest')['foot', 'fell', 'fastest']
re.sub(r'(\b[a-z]+) \1', r'\1', 'cat in the the hat')'cat in the hat'
当只需要简单的功能时，字符串方法是首选，因为它们更容易阅读和调试：
'tea for too'.replace('too', 'two')'tea for two'
数学
数学模块可以访问浮点数学的底层C库函数：
import math
math.cos(math.pi / 4)0.7071067811865476
math.log(1.24, 2)0.3103401206121505
random模块提供了随机选择的工具：
import random
random.choice(['apple', 'pear', 'banana'])'apple'
random.sample(range(100), 10) # sampling without replacement[71, 15, 11, 61, 92, 52, 56, 79, 45, 33]
random.random() # random float0.22912587343791546
random.randrange(6) # random integer chosen from range(6)0
统计模块计算数字数据的基本统计属性（平均值，中位数，方差等）：
import statistics
data = [2.75, 1.75, 1.25, 0.25, 0.5, 1.25, 3.5]
statistics.mean(data)1.6071428571428572
statistics.median(data)1.25
statistics.variance(data)1.3720238095238095
SciPy项目有许多其他数值计算模块。
网络访问
有许多模块可用于访问互联网和处理互联网协议。 其中最简单的两个是urllib.request，用于从URL和smtplib中检索数据以发送邮件：
from urllib.request import urlopen
with urlopen('http://tycho.usno.navy.mil/cgi-bin/timer.pl') as response:
for line in response:
line = line.decode('utf-8') # Decoding the binary data to next.
if 'EST' in line or 'EDT' in line: # look for Eastern Time
print(line)import smtplib
server = smtplib.SMTP('localhost')
server.sendmail('[email protected]', '[email protected]',
"""To：[email protected]
From：[email protected]
Beware the Ides of March""")
server.quit()---------------------------------------------------------------------------
ConnectionRefusedError Traceback (most recent call last)
<ipython-input-34-776db08e494f> in <module>()
1 import smtplib
----> 2 server = smtplib.SMTP('localhost')
3 server.sendmail('[email protected]', '[email protected]',
4 """To：[email protected]
5 From：[email protected]
C:\Python34\lib\smtplib.py in __init__(self, host, port, local_hostname, timeout, source_address)
240
241 if host:
--> 242 (code, msg) = self.connect(host, port)
243 if code != 220:
244 raise SMTPConnectError(code, msg)
C:\Python34\lib\smtplib.py in connect(self, host, port, source_address)
319 if self.debuglevel > 0:
320 print('connect:', (host, port), file=stderr)
--> 321 self.sock = self._get_socket(host, port, self.timeout)
322 self.file = None
323 (code, msg) = self.getreply()
C:\Python34\lib\smtplib.py in _get_socket(self, host, port, timeout)
290 file=stderr)
291 return socket.create_connection((host, port), timeout,
--> 292 self.source_address)
293
294 def connect(self, host='localhost', port=0, source_address=None):
C:\Python34\lib\socket.py in create_connection(address, timeout, source_address)
514
515 if err is not None:
--> 516 raise err
517 else:
518 raise error("getaddrinfo returns an empty list")
C:\Python34\lib\socket.py in create_connection(address, timeout, source_address)
505 if source_address:
506 sock.bind(source_address)
--> 507 sock.connect(sa)
508 return sock
509
ConnectionRefusedError: [WinError 10061] 由于目标计算机积极拒绝，无法连接。
（请注意，第二个示例需要在本地主机上运行的邮件服务器。）
日期和时间
虽然支持日期和时间算术，但实现的重点在于为输出格式化和操作提供有效的成员提取。 该模块还支持时区感知的对象。datetime模块提供了以简单和复杂的方式操作时间和日期的类。
# dates are easily constructed and formatted
from datetime import date
now = date.today()
nowdatetime.date(2018, 6, 16)
now.strftime("%m-%d-%y. %d %b %Y is a %A on the %d day of %B.")'06-16-18. 16 Jun 2018 is a Saturday on the 16 day of June.'
# dates support calendar arithmetic
birthday = date(1964, 7, 31)
age = now - birthday
age.days19678
日期压缩
通用数据归档和压缩格式直接受模块支持，包括：zlib，gzip，bz2，lzma，zipfile和tarfile。
import zlib
s = b'witch which has which witches wirst watch'
len(s)41
t = zlib.compress(s)
len(t)37
zlib.decompress(t)b'witch which has which witches wirst watch'
zlib.crc32(s)4234112616
表现衡量
一些Python用户对了解同一问题的不同方法的相对性能产生了浓厚的兴趣。 Python提供了一个即时回答这些问题的测量工具。
例如，使用元组打包和解包功能可能很诱人，而不是传统的方法来交换参数。 timeit模块很快显示出适度的性能优势：
from timeit import Timer
Timer('t=a; a=b; b=t', 'a=1; b=2').timeit()0.04052831188938733
Timer('a,b = b, a', 'a=1; b=2').timeit()0.03597679448774471
与timeit的精细粒度级别相比，profile和pstats模块提供了用于识别更大代码块中的时间关键部分的工具。
质量控制
开发高质量软件的一种方法是在开发过程中为每个函数编写测试，并在开发过程中频繁运行这些测试。
doctest模块提供了一个工具，用于扫描模块并验证程序文档中嵌入的测试。 测试的结构就像将一个典型的调用和结果切入并粘贴到文档字符串一样简单。 这通过向用户提供示例来改进文档，并且它允许doctest模块确保代码对文档保持真实：
def average(values):
"""Computes the arithmetic mean of a list of numbers.
>>> print(average([20, 30, 70]))
40.0
"""
return sum(values) / len(values)
import doctest
doctest.testmod() # automatically validate the embedded testsTestResults(failed=0, attempted=1)
unittest模块不像doctest模块那样容易，但它允许在一个单独的文件中维护更全面的一组测试：
import unittest
class TestStatisticalFunctions(unittest.TestCase):
def test_average(self):
self.assertEqual(average([20, 30, 70]), 40.0)
self.assertEqual(round(average([1, 5, 7]), 1), 4.3)
with self.assertRaises(ZeroDivisionError):
average([])
with self.assertRaises(TypeError):
average(20, 30, 70)
unittest.main() # Calling from the command line invokes all testsBatteries Included
Python有一个“batteries included”的理念。 通过其大型软件包的复杂而强大的功能，可以很好地看到这一点。 例如：
- xmlrpc.client和xmlrpc.server模块使得实现远程过程调用变成了一项几乎微不足道的任务。尽管有模块名称，但不需要直接了解或处理XML。
- 电子邮件包是用于管理电子邮件消息的库，包括MIME和其他基于RFC 2822的消息文档。与实际发送和接收消息的smtplib和poplib不同，电子邮件包具有一个完整的工具集，用于构建或解码复杂的消息结构（包括附件）以及实现互联网编码和头协议。
- json包为解析这种流行的数据交换格式提供了强大的支持。 csv模块支持以逗号分隔值(Comma-Separated Value format)格式直接读取和写入文件，通常由数据库和电子表格支持。 XML处理由xml.etree.ElementTree，xml.dom和xml.sax包支持。这些模块和包一起大大简化了Python应用程序和其他工具之间的数据交换。
- sqlite3模块是SQLite数据库库的一个包装，提供了一个持久数据库，可以使用稍微非标准的SQL语法来更新和访问。
- 国际化由许多模块支持，包括gettext，locale和编解码器包。