【语法11】Python标准库

操作系统接口

os模块提供了不少与操作系统相关联的函数。

import os
os.chdir(r'C:\Users\asus\Python')
print(os.getcwd()) #返回当前的工作目录

os.chdir(r'C:\Users\asus\Python\tmp')#修改当前的工作目录
print(os.getcwd())

#建议使用 "import os" 风格而非 "from os import *"。这样可以保证随操作系统不同而有所变化的 os.open() 不会覆盖内置函数 open()。

C:\Users\asus\Python
C:\Users\asus\Python\tmp

#在使用 os 这样的大型模块时内置的 dir() 和 help() 函数非常有用
import os
print(dir(os))

print(help(os))

['DirEntry', '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', 'PathLike', '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', '_fspath', '_get_exports_list', '_putenv', '_unsetenv', '_wrap_close', 'abc', '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', 'fspath', 'fstat', 'fsync', 'ftruncate', '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', 'scandir', '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', 'truncate', 'umask', 'uname_result', 'unlink', 'urandom', 'utime', 'waitpid', 'walk', 'write']
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 or nt, e.g. unlink, stat, etc.
      - os.path is either posixpath or ntpath
      - os.name is either 'posix' or 'nt'
      - os.curdir is a string representing the current directory (always '.')
      - os.pardir is a string representing the parent directory (always '..')
      - os.sep is the (or a most common) pathname separator ('/' 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.object
        nt.DirEntry
    builtins.tuple(builtins.object)
        nt.times_result
        nt.uname_result
        stat_result
        statvfs_result
        terminal_size
    
    class DirEntry(builtins.object)
     |  Methods defined here:
     |  
     |  __fspath__(...)
     |      returns the path for the entry
     |  
     |  __repr__(self, /)
     |      Return repr(self).
     |  
     |  inode(...)
     |      return inode of the entry; cached per entry
     |  
     |  is_dir(...)
     |      return True if the entry is a directory; cached per entry
     |  
     |  is_file(...)
     |      return True if the entry is a file; cached per entry
     |  
     |  is_symlink(...)
     |      return True if the entry is a symbolic link; cached per entry
     |  
     |  stat(...)
     |      return stat_result object for the entry; cached per entry
     |  
     |  ----------------------------------------------------------------------
     |  Data descriptors defined here:
     |  
     |  name
     |      the entry's base filename, relative to scandir() "path" argument
     |  
     |  path
     |      the entry's full path name; equivalent to os.path.join(scandir_path, entry.name)
    
    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__(...)
     |      helper for pickle
     |  
     |  __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__(...)
     |      helper for pickle
     |  
     |  __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_file_attributes
     |      Windows file attribute bits
     |  
     |  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 = 17
     |  
     |  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__(...)
     |      helper for pickle
     |  
     |  __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(v