
``os.path`` --- Common pathname manipulations
*********************************************

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 either strings, or
bytes. Applications are encouraged to represent file names as
(Unicode) character strings. Unfortunately, some file names may not be
representable as strings on Unix, so applications that need to support
arbitrary file names on Unix should use bytes objects to represent
path names. Vice versa, using bytes objects cannot represent all file
names on Windows (in the standard ``mbcs`` encoding), hence Windows
applications should use string objects to access all files.

Note: 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.

Warning: On Windows, many of these functions do not properly support UNC
  pathnames. ``splitunc()`` and ``ismount()`` do handle them
  correctly.

os.path.abspath(path)

   Return a normalized absolutized version of the pathname *path*. On
   most platforms, this is equivalent to ``normpath(join(os.getcwd(),
   path))``.

os.path.basename(path)

   Return the base name of pathname *path*.  This is the second half
   of the pair returned by ``split(path)``.  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 (``''``).

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 (``''``). Note that this may return invalid paths
   because it works a character at a time.

os.path.dirname(path)

   Return the directory name of pathname *path*.  This is the first
   half of the pair returned by ``split(path)``.

os.path.exists(path)

   Return ``True`` if *path* refers to an existing path.  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.

os.path.lexists(path)

   Return ``True`` if *path* refers to an existing path. Returns
   ``True`` for broken symbolic links.   Equivalent to ``exists()`` on
   platforms lacking ``os.lstat()``.

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, **HOME** and **USERPROFILE** will be used if set,
   otherwise a combination of **HOMEPATH** and **HOMEDRIVE** will be
   used.  An initial ``~user`` is handled by stripping the last
   directory component from the created user path derived above.

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

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}``.

os.path.getatime(path)

   Return the time of last access of *path*.  The return value is a
   number giving the number of seconds since the epoch (see the
   ``time`` module).  Raise ``os.error`` if the file does not exist or
   is inaccessible.

   If ``os.stat_float_times()`` returns True, the result is a floating
   point number.

os.path.getmtime(path)

   Return the time of last modification of *path*.  The return value
   is a number giving the number of seconds since the epoch (see the
   ``time`` module). Raise ``os.error`` if the file does not exist or
   is inaccessible.

   If ``os.stat_float_times()`` returns True, the result is a floating
   point number.

os.path.getctime(path)

   Return the system's ctime which, on some systems (like Unix) is the
   time of the last 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 ``os.error`` if the file does not exist or is inaccessible.

os.path.getsize(path)

   Return the size, in bytes, of *path*.  Raise ``os.error`` if the
   file does not exist or is inaccessible.

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.

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.

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.

os.path.islink(path)

   Return ``True`` if *path* refers to a directory entry that is a
   symbolic link. Always ``False`` if symbolic links are not
   supported.

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.  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.

os.path.join(path1[, path2[, ...]])

   Join one or more path components intelligently.  If any component
   is an absolute path, all previous components (on Windows, including
   the previous drive letter, if there was one) are thrown away, and
   joining continues.  The return value is the concatenation of
   *path1*, and optionally *path2*, etc., with exactly one directory
   separator (``os.sep``) inserted between components, unless *path2*
   is empty.  Note that on Windows, 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``.

os.path.normcase(path)

   Normalize the case of a pathname.  On Unix and MacOSX, this returns
   the path unchanged; on case-insensitive filesystems, it converts
   the path to lowercase.  On Windows, it also converts forward
   slashes to backward slashes.

os.path.normpath(path)

   Normalize a pathname.  This collapses redundant separators and up-
   level references so that ``A//B``, ``A/./B`` and ``A/foo/../B`` all
   become ``A/B``. It does not normalize the case (use ``normcase()``
   for that).  On Windows, it converts forward slashes to backward
   slashes. It should be understood that this may change the meaning
   of the path if it contains symbolic links!

os.path.realpath(path)

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

os.path.relpath(path[, start])

   Return a relative filepath to *path* either from the current
   directory or from an optional *start* point.

   *start* defaults to ``os.curdir``. Availability:  Windows, Unix.

os.path.samefile(path1, path2)

   Return ``True`` if both pathname arguments refer to the same file
   or directory (as indicated by device number and i-node number).
   Raise an exception if a ``os.stat()`` call on either pathname
   fails. Availability: Unix.

os.path.sameopenfile(fp1, fp2)

   Return ``True`` if the file descriptors *fp1* and *fp2* refer to
   the same file. Availability: Unix.

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 ``fstat()``,
   ``lstat()``, or ``stat()``.  This function implements the
   underlying comparison used by ``samefile()`` and
   ``sameopenfile()``. Availability: Unix.

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 nearly all
   cases, ``join(head, tail)`` equals *path* (the only exception being
   when there were multiple slashes separating *head* from *tail*).

os.path.splitdrive(path)

   Split the pathname *path* into a pair ``(drive, tail)`` where
   *drive* is either a drive specification 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*.

os.path.splitext(path)

   Split the pathname *path* into a pair ``(root, ext)``  such that
   ``root + ext == path``, and *ext* is empty or begins with a period
   and contains at most one period. Leading periods on the basename
   are  ignored; ``splitext('.cshrc')`` returns  ``('.cshrc', '')``.

os.path.splitunc(path)

   Split the pathname *path* into a pair ``(unc, rest)`` so that *unc*
   is the UNC mount point (such as ``r'\\host\mount'``), if present,
   and *rest* the rest of the path (such as  ``r'\path\file.ext'``).
   For paths containing drive letters, *unc* will always be the empty
   string. Availability:  Windows.

os.path.supports_unicode_filenames

   True if arbitrary Unicode strings can be used as file names (within
   limitations imposed by the file system), and if ``os.listdir()``
   returns strings that contain characters that cannot be represented
   by ASCII.
