os.path — Common pathname manipulations

Source code: Lib/genericpath.py, Lib/posixpath.py (for POSIX) and Lib/ntpath.py (for Windows).

This module implements some useful functions on pathnames. To read or write files see open(), and for accessing the filesystem see the os module. The path parameters can be passed as strings, or bytes, or any object implementing the os.PathLike protocol.

Unlike a Unix shell, Python does not do any automatic path expansions. Functions such as expanduser() and expandvars() can be invoked explicitly when an application desires shell-like path expansion. (See also the glob module.)

Zobacz także

The pathlib module offers high-level path objects.

Informacja

All of these functions accept either only bytes or only string objects as their parameters. The result is an object of the same type, if a path or file name is returned.

Informacja

Since different operating systems have different path name conventions, there are several versions of this module in the standard library. The os.path module is always the path module suitable for the operating system Python is running on, and therefore usable for local paths. However, you can also import and use the individual modules if you want to manipulate a path that is always in one of the different formats. They all have the same interface:

  • posixpath for UNIX-style paths

  • ntpath for Windows paths

Zmienione w wersji 3.8: exists(), lexists(), isdir(), isfile(), islink(), and ismount() now return False instead of raising an exception for paths that contain characters or bytes unrepresentable at the OS level.

os.path.abspath(path)

Return a normalized absolutized version of the pathname path. On most platforms, this is equivalent to calling the function normpath() as follows: normpath(join(os.getcwd(), path)).

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.basename(path)

Return the base name of pathname path. This is the second element of the pair returned by passing path to the function split(). Note that the result of this function is different from the Unix basename program; where basename for '/foo/bar/' returns 'bar', the basename() function returns an empty string ('').

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.commonpath(paths)

Return the longest common sub-path of each pathname in the sequence paths. Raise ValueError if paths contain both absolute and relative pathnames, if paths are on different drives, or if paths is empty. Unlike commonprefix(), this returns a valid path.

Added in version 3.5.

Zmienione w wersji 3.6: Accepts a sequence of path-like objects.

os.path.commonprefix(list)

Return the longest path prefix (taken character-by-character) that is a prefix of all paths in list. If list is empty, return the empty string ('').

Informacja

This function may return invalid paths because it works a character at a time. To obtain a valid path, see commonpath().

>>> os.path.commonprefix(['/usr/lib', '/usr/local/lib'])
'/usr/l'

>>> os.path.commonpath(['/usr/lib', '/usr/local/lib'])
'/usr'

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.dirname(path)

Return the directory name of pathname path. This is the first element of the pair returned by passing path to the function split().

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.exists(path)

Return True if path refers to an existing path or an open file descriptor. Returns False for broken symbolic links. On some platforms, this function may return False if permission is not granted to execute os.stat() on the requested file, even if the path physically exists.

Zmienione w wersji 3.3: path can now be an integer: True is returned if it is an open file descriptor, False otherwise.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.lexists(path)

Return True if path refers to an existing path, including broken symbolic links. Equivalent to exists() on platforms lacking os.lstat().

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.expanduser(path)

On Unix and Windows, return the argument with an initial component of ~ or ~user replaced by that user’s home directory.

On Unix, an initial ~ is replaced by the environment variable HOME if it is set; otherwise the current user’s home directory is looked up in the password directory through the built-in module pwd. An initial ~user is looked up directly in the password directory.

On Windows, USERPROFILE will be used if set, otherwise a combination of HOMEPATH and HOMEDRIVE will be used. An initial ~user is handled by checking that the last directory component of the current user’s home directory matches USERNAME, and replacing it if so.

If the expansion fails or if the path does not begin with a tilde, the path is returned unchanged.

Zmienione w wersji 3.6: Accepts a path-like object.

Zmienione w wersji 3.8: No longer uses HOME on Windows.

os.path.expandvars(path)

Return the argument with environment variables expanded. Substrings of the form $name or ${name} are replaced by the value of environment variable name. Malformed variable names and references to non-existing variables are left unchanged.

On Windows, %name% expansions are supported in addition to $name and ${name}.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.getatime(path)

Return the time of last access of path. The return value is a floating-point number giving the number of seconds since the epoch (see the time module). Raise OSError if the file does not exist or is inaccessible.

os.path.getmtime(path)

Return the time of last modification of path. The return value is a floating-point number giving the number of seconds since the epoch (see the time module). Raise OSError if the file does not exist or is inaccessible.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.getctime(path)

Return the system’s ctime which, on some systems (like Unix) is the time of the last metadata change, and, on others (like Windows), is the creation time for path. The return value is a number giving the number of seconds since the epoch (see the time module). Raise OSError if the file does not exist or is inaccessible.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.getsize(path)

Return the size, in bytes, of path. Raise OSError if the file does not exist or is inaccessible.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.isabs(path)

Return True if path is an absolute pathname. On Unix, that means it begins with a slash, on Windows that it begins with a (back)slash after chopping off a potential drive letter.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.isfile(path)

Return True if path is an existing regular file. This follows symbolic links, so both islink() and isfile() can be true for the same path.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.isdir(path)

Return True if path is an existing directory. This follows symbolic links, so both islink() and isdir() can be true for the same path.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.isjunction(path)

Return True if path refers to an existing directory entry that is a junction. Always return False if junctions are not supported on the current platform.

Added in version 3.12.

Return True if path refers to an existing directory entry that is a symbolic link. Always False if symbolic links are not supported by the Python runtime.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.ismount(path)

Return True if pathname path is a mount point: a point in a file system where a different file system has been mounted. On POSIX, the function checks whether path’s parent, path/.., is on a different device than path, or whether path/.. and path point to the same i-node on the same device — this should detect mount points for all Unix and POSIX variants. It is not able to reliably detect bind mounts on the same filesystem. On Windows, a drive letter root and a share UNC are always mount points, and for any other path GetVolumePathName is called to see if it is different from the input path.

Zmienione w wersji 3.4: Added support for detecting non-root mount points on Windows.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.isdevdrive(path)

Return True if pathname path is located on a Windows Dev Drive. A Dev Drive is optimized for developer scenarios, and offers faster performance for reading and writing files. It is recommended for use for source code, temporary build directories, package caches, and other IO-intensive operations.

May raise an error for an invalid path, for example, one without a recognizable drive, but returns False on platforms that do not support Dev Drives. See the Windows documentation for information on enabling and creating Dev Drives.

Availability: Windows.

Added in version 3.12.

os.path.join(path, *paths)

Join one or more path segments intelligently. The return value is the concatenation of path and all members of *paths, with exactly one directory separator following each non-empty part, except the last. That is, the result will only end in a separator if the last part is either empty or ends in a separator. If a segment is an absolute path (which on Windows requires both a drive and a root), then all previous segments are ignored and joining continues from the absolute path segment.

On Windows, the drive is not reset when a rooted path segment (e.g., r'\foo') is encountered. If a segment is on a different drive or is an absolute path, all previous segments are ignored and the drive is reset. Note that since there is a current directory for each drive, os.path.join("c:", "foo") represents a path relative to the current directory on drive C: (c:foo), not c:\foo.

Zmienione w wersji 3.6: Accepts a path-like object for path and paths.

os.path.normcase(path)

Normalize the case of a pathname. On Windows, convert all characters in the pathname to lowercase, and also convert forward slashes to backward slashes. On other operating systems, return the path unchanged.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.normpath(path)

Normalize a pathname by collapsing redundant separators and up-level references so that A//B, A/B/, A/./B and A/foo/../B all become A/B. This string manipulation may change the meaning of a path that contains symbolic links. On Windows, it converts forward slashes to backward slashes. To normalize case, use normcase().

Informacja

On POSIX systems, in accordance with IEEE Std 1003.1 2013 Edition; 4.13 Pathname Resolution, if a pathname begins with exactly two slashes, the first component following the leading characters may be interpreted in an implementation-defined manner, although more than two leading characters shall be treated as a single character.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.realpath(path, *, strict=False)

Return the canonical path of the specified filename, eliminating any symbolic links encountered in the path (if they are supported by the operating system).

If a path doesn’t exist or a symlink loop is encountered, and strict is True, OSError is raised. If strict is False, the path is resolved as far as possible and any remainder is appended without checking whether it exists.

Informacja

This function emulates the operating system’s procedure for making a path canonical, which differs slightly between Windows and UNIX with respect to how links and subsequent path components interact.

Operating system APIs make paths canonical as needed, so it’s not normally necessary to call this function.

Zmienione w wersji 3.6: Accepts a path-like object.

Zmienione w wersji 3.8: Symbolic links and junctions are now resolved on Windows.

Zmienione w wersji 3.10: Parametr strict został dodany.

os.path.relpath(path, start=os.curdir)

Return a relative filepath to path either from the current directory or from an optional start directory. This is a path computation: the filesystem is not accessed to confirm the existence or nature of path or start. On Windows, ValueError is raised when path and start are on different drives.

start defaults to os.curdir.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.samefile(path1, path2)

Return True if both pathname arguments refer to the same file or directory. This is determined by the device number and i-node number and raises an exception if an os.stat() call on either pathname fails.

Zmienione w wersji 3.2: Dodano wsparcie dla WIndowsa.

Zmienione w wersji 3.4: Windows now uses the same implementation as all other platforms.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.sameopenfile(fp1, fp2)

Return True if the file descriptors fp1 and fp2 refer to the same file.

Zmienione w wersji 3.2: Dodano wsparcie dla WIndowsa.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.samestat(stat1, stat2)

Return True if the stat tuples stat1 and stat2 refer to the same file. These structures may have been returned by os.fstat(), os.lstat(), or os.stat(). This function implements the underlying comparison used by samefile() and sameopenfile().

Zmienione w wersji 3.4: Dodano wsparcie dla WIndowsa.

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.split(path)

Split the pathname path into a pair, (head, tail) where tail is the last pathname component and head is everything leading up to that. The tail part will never contain a slash; if path ends in a slash, tail will be empty. If there is no slash in path, head will be empty. If path is empty, both head and tail are empty. Trailing slashes are stripped from head unless it is the root (one or more slashes only). In all cases, join(head, tail) returns a path to the same location as path (but the strings may differ). Also see the functions dirname() and basename().

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.splitdrive(path)

Split the pathname path into a pair (drive, tail) where drive is either a mount point or the empty string. On systems which do not use drive specifications, drive will always be the empty string. In all cases, drive + tail will be the same as path.

On Windows, splits a pathname into drive/UNC sharepoint and relative path.

If the path contains a drive letter, drive will contain everything up to and including the colon:

>>> splitdrive("c:/dir")
("c:", "/dir")

If the path contains a UNC path, drive will contain the host name and share:

>>> splitdrive("//host/computer/dir")
("//host/computer", "/dir")

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.splitroot(path)

Split the pathname path into a 3-item tuple (drive, root, tail) where drive is a device name or mount point, root is a string of separators after the drive, and tail is everything after the root. Any of these items may be the empty string. In all cases, drive + root + tail will be the same as path.

On POSIX systems, drive is always empty. The root may be empty (if path is relative), a single forward slash (if path is absolute), or two forward slashes (implementation-defined per IEEE Std 1003.1-2017; 4.13 Pathname Resolution.) For example:

>>> splitroot('/home/sam')
('', '/', 'home/sam')
>>> splitroot('//home/sam')
('', '//', 'home/sam')
>>> splitroot('///home/sam')
('', '/', '//home/sam')

On Windows, drive may be empty, a drive-letter name, a UNC share, or a device name. The root may be empty, a forward slash, or a backward slash. For example:

>>> splitroot('C:/Users/Sam')
('C:', '/', 'Users/Sam')
>>> splitroot('//Server/Share/Users/Sam')
('//Server/Share', '/', 'Users/Sam')

Added in version 3.12.

os.path.splitext(path)

Split the pathname path into a pair (root, ext) such that root + ext == path, and the extension, ext, is empty or begins with a period and contains at most one period.

If the path contains no extension, ext will be '':

>>> splitext('bar')
('bar', '')

If the path contains an extension, then ext will be set to this extension, including the leading period. Note that previous periods will be ignored:

>>> splitext('foo.bar.exe')
('foo.bar', '.exe')
>>> splitext('/foo/bar.exe')
('/foo/bar', '.exe')

Leading periods of the last component of the path are considered to be part of the root:

>>> splitext('.cshrc')
('.cshrc', '')
>>> splitext('/foo/....jpg')
('/foo/....jpg', '')

Zmienione w wersji 3.6: Accepts a path-like object.

os.path.supports_unicode_filenames

True if arbitrary Unicode strings can be used as file names (within limitations imposed by the file system).