# 6.2 `os.path` -- Common pathname manipulations

This module implements some useful functions on pathnames.

`abspath` (path)
  Return a normalized absolutized version of the pathname path. On most platforms, this is equivalent to `normpath(join(os.getcwd(), path))`. New in version 1.5.2.

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

`commonprefix` (list)
  Return the longest string that is a prefix of all strings in list. If list is empty, return the empty string (`''`).

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

`exists` (path)
  Return true if path refers to an existing path.

`expanduser` (path)
  Return the argument with an initial component of "`~`" or "`~user`" replaced by that user's home directory. An initial "`~`" is replaced by the environment variable $HOME; an initial "`~user`" is looked up in the password directory through the built-in module `pwd`. If the expansion fails, or if the path does not begin with a tilde, the path is returned unchanged. On the Macintosh, this always returns path unchanged.

`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 the Macintosh, this always returns path unchanged.

`getatime` (path)
  Return the time of last access of filename. The return value is integer giving the number of seconds since the epoch (see the `time` module). Raise `os.error` if the file does not exist or is inaccessible. New in version 1.5.2.

`getmtime` (path)
  Return the time of last modification of filename. The return value is integer giving the number of seconds since the epoch (see the `time` module). Raise `os.error` if the file does not exist or is inaccessible. New in version 1.5.2.

`getsize` (path)
  Return the size, in bytes, of filename. Raise `os.error` if the file does not exist or is inaccessible. New in version 1.5.2.

`isabs` (path)
  Return true if path is an absolute pathname (begins with a slash).

`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.

`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.

`islink` (path)
  Return true if path refers to a directory entry that is a symbolic link. Always false if symbolic links are not supported.

`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.

`join` (path1[, path2[, ...]])
  Joins one or more path components intelligently. If any component is an absolute path, all previous components are thrown away, and joining continues. The return value is the concatenation of path1, and optionally path2, etc., with exactly one slash (`'/'`) inserted between components, unless path is empty.

`normcase` (path)
  Normalize the case of a pathname. On Unix, 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.

`normpath` (path)
  Normalize a pathname. This collapses redundant separators and up-level references, e.g. `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.

`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: Macintosh, Unix.

`sameopenfile` (fp1, fp2)
  Return true if the file objects fp1 and fp2 refer to the same file. The two file objects may represent different file descriptors. Availability: Macintosh, Unix.

`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: Macintosh, Unix.

`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).

`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.

`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.

`walk` (path, visit, arg)
  Calls the function visit with arguments `(arg, dirname, names)` for each directory in the directory tree rooted at path (including path itself, if it is a directory). The argument dirname specifies the visited directory, the argument names lists the files in the directory (gotten from `os.listdir(dirname)`). The visit function may modify names to influence the set of directories visited below dirname, e.g., to avoid visiting certain parts of the tree. (The object referred to by names must be modified in place, using `del` or slice assignment.)