os.path
--- Common pathname manipulations¶
Source code: Lib/posixpath.py (for POSIX), Lib/ntpath.py (for Windows NT), and Lib/macpath.py (for Macintosh)
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.
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.)
也參考
The pathlib
module offers high-level path objects.
備註
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.
備註
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 pathsntpath
for Windows pathsmacpath
for old-style MacOS paths
-
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))
.3.6 版更變: 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'
, thebasename()
function returns an empty string (''
).3.6 版更變: 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 contains both absolute and relative pathnames, or if paths is empty. Unlikecommonprefix()
, this returns a valid path.Availability: Unix, Windows.
3.5 版新加入.
3.6 版更變: 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 (
''
).備註
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'
3.6 版更變: 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()
.3.6 版更變: Accepts a path-like object.
-
os.path.
exists
(path)¶ Return
True
if path refers to an existing path or an open file descriptor. ReturnsFalse
for broken symbolic links. On some platforms, this function may returnFalse
if permission is not granted to executeos.stat()
on the requested file, even if the path physically exists.3.3 版更變: path can now be an integer:
True
is returned if it is an open file descriptor,False
otherwise.3.6 版更變: Accepts a path-like object.
-
os.path.
lexists
(path)¶ Return
True
if path refers to an existing path. ReturnsTrue
for broken symbolic links. Equivalent toexists()
on platforms lackingos.lstat()
.3.6 版更變: 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 variableHOME
if it is set; otherwise the current user's home directory is looked up in the password directory through the built-in modulepwd
. An initial~user
is looked up directly in the password directory.On Windows,
HOME
andUSERPROFILE
will be used if set, otherwise a combination ofHOMEPATH
andHOMEDRIVE
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.
3.6 版更變: Accepts a path-like object.
-
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}
.3.6 版更變: 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). RaiseOSError
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). RaiseOSError
if the file does not exist or is inaccessible.3.6 版更變: 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). RaiseOSError
if the file does not exist or is inaccessible.3.6 版更變: 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.3.6 版更變: 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.3.6 版更變: Accepts a path-like object.
-
os.path.
isfile
(path)¶ Return
True
if path is anexisting
regular file. This follows symbolic links, so bothislink()
andisfile()
can be true for the same path.3.6 版更變: Accepts a path-like object.
-
os.path.
isdir
(path)¶ Return
True
if path is anexisting
directory. This follows symbolic links, so bothislink()
andisdir()
can be true for the same path.3.6 版更變: Accepts a path-like object.
-
os.path.
islink
(path)¶ Return
True
if path refers to anexisting
directory entry that is a symbolic link. AlwaysFalse
if symbolic links are not supported by the Python runtime.3.6 版更變: 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 whetherpath/..
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 pathGetVolumePathName
is called to see if it is different from the input path.3.4 版新加入: Support for detecting non-root mount points on Windows.
3.6 版更變: Accepts a path-like object.
-
os.path.
join
(path, *paths)¶ Join one or more path components intelligently. The return value is the concatenation of path and any members of *paths with exactly one directory separator (
os.sep
) following each non-empty part except the last, meaning that the result will only end in a separator if the last part is empty. If a component is an absolute path, all previous components are thrown away and joining continues from the absolute path component.On Windows, the drive letter is not reset when an absolute path component (e.g.,
r'\foo'
) is encountered. If a component contains a drive letter, all previous components are thrown away and the drive letter 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 driveC:
(c:foo
), notc:\foo
.3.6 版更變: 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. Raise a
TypeError
if the type of path is notstr
orbytes
(directly or indirectly through theos.PathLike
interface).3.6 版更變: 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
andA/foo/../B
all becomeA/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, usenormcase()
.3.6 版更變: Accepts a path-like object.
-
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).
3.6 版更變: Accepts a path-like object.
-
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.
start defaults to
os.curdir
.Availability: Unix, Windows.
3.6 版更變: 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 anos.stat()
call on either pathname fails.Availability: Unix, Windows.
3.2 版更變: Added Windows support.
3.4 版更變: Windows now uses the same implementation as all other platforms.
3.6 版更變: Accepts a path-like object.
-
os.path.
sameopenfile
(fp1, fp2)¶ Return
True
if the file descriptors fp1 and fp2 refer to the same file.Availability: Unix, Windows.
3.2 版更變: Added Windows support.
3.6 版更變: 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 byos.fstat()
,os.lstat()
, oros.stat()
. This function implements the underlying comparison used bysamefile()
andsameopenfile()
.Availability: Unix, Windows.
3.4 版更變: Added Windows support.
3.6 版更變: 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 functionsdirname()
andbasename()
.3.6 版更變: 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. e.g.
splitdrive("c:/dir")
returns("c:", "/dir")
If the path contains a UNC path, drive will contain the host name and share, up to but not including the fourth separator. e.g.
splitdrive("//host/computer/dir")
returns("//host/computer", "/dir")
3.6 版更變: Accepts a path-like object.
-
os.path.
splitext
(path)¶ Split the pathname path into a pair
(root, ext)
such thatroot + 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', '')
.3.6 版更變: 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).