11.2.os.path — Common pathname manipulations

Source code:Lib/posixpath.py (for POSIX),Lib/ntpath.py (for Windows NT),andLib/macpath.py (for Macintosh)

This module implements some useful functions on pathnames. To read orwrite files seeopen(), and for accessing the filesystem see theos 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 berepresentable as strings on Unix, so applications that need to supportarbitrary file names on Unix should use bytes objects to representpath names. Vice versa, using bytes objects cannot represent all filenames on Windows (in the standardmbcs encoding), hence Windowsapplications should use string objects to access all files.

Unlike a unix shell, Python does not do anyautomatic path expansions.Functions such asexpanduser() andexpandvars() can be invokedexplicitly when an application desires shell-like path expansion. (See alsotheglob module.)

See also

Thepathlib module offers high-level path objects.

Note

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

Note

Since different operating systems have different path name conventions, thereare several versions of this module in the standard library. Theos.path module is always the path module suitable for the operatingsystem Python is running on, and therefore usable for local paths. However,you can also import and use the individual modules if you want to manipulatea path that isalways in one of the different formats. They all have thesame interface:

  • posixpath for UNIX-style paths
  • ntpath for Windows paths
  • macpath for old-style MacOS paths
os.path.abspath(path)

Return a normalized absolutized version of the pathnamepath. On mostplatforms, this is equivalent to calling the functionnormpath() asfollows:normpath(join(os.getcwd(),path)).

os.path.basename(path)

Return the base name of pathnamepath. This is the second element of thepair returned by passingpath to the functionsplit(). Note thatthe result of this function is differentfrom the Unixbasename program; wherebasename for'/foo/bar/' returns'bar', thebasename() function returns anempty string ('').

os.path.commonpath(paths)

Return the longest common sub-path of each pathname in the sequencepaths. Raise ValueError ifpaths contains both absolute and relativepathnames, or ifpaths is empty. Unlikecommonprefix(), thisreturns a valid path.

Availability: Unix, Windows

New in version 3.5.

os.path.commonprefix(list)

Return the longest path prefix (taken character-by-character) that is aprefix of all paths inlist. Iflist is empty, return the empty string('').

Note

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

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

Return the directory name of pathnamepath. This is the first element ofthe pair returned by passingpath to the functionsplit().

os.path.exists(path)

ReturnTrue ifpath refers to an existing path or an openfile descriptor. ReturnsFalse for broken symbolic links. Onsome platforms, this function may returnFalse if permission isnot granted to executeos.stat() on the requested file, evenif thepath physically exists.

Changed in version 3.3:path can now be an integer:True is returned if it is an open file descriptor,False otherwise.

os.path.lexists(path)

ReturnTrue ifpath refers to an existing path. ReturnsTrue forbroken symbolic links. Equivalent toexists() on platforms lackingos.lstat().

os.path.expanduser(path)

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

On Unix, an initial~ is replaced by the environment variableHOMEif it is set; otherwise the current user’s home directory is looked up in thepassword directory through the built-in modulepwd. An initial~useris looked up directly in the password directory.

On Windows,HOME andUSERPROFILE will be used if set,otherwise a combination ofHOMEPATH andHOMEDRIVE will beused. An initial~user is handled by stripping the last directory componentfrom the created user path derived above.

If the expansion fails or if the path does not begin with a tilde, the path isreturned 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 variablename. Malformed variable names and references to non-existing variables areleft unchanged.

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

os.path.getatime(path)

Return the time of last access ofpath. The return value is a number givingthe number of seconds since the epoch (see thetime module). RaiseOSError if the file does not exist or is inaccessible.

Ifos.stat_float_times() returnsTrue, the result is a floating pointnumber.

os.path.getmtime(path)

Return the time of last modification ofpath. The return value is a numbergiving the number of seconds since the epoch (see thetime module).RaiseOSError if the file does not exist or is inaccessible.

Ifos.stat_float_times() returnsTrue, the result is a floating pointnumber.

os.path.getctime(path)

Return the system’s ctime which, on some systems (like Unix) is the time of thelast metadata change, and, on others (like Windows), is the creation time forpath.The return value is a number giving the number of seconds since the epoch (seethetime module). RaiseOSError if the file does not exist oris inaccessible.

os.path.getsize(path)

Return the size, in bytes, ofpath. RaiseOSError if the file doesnot exist or is inaccessible.

os.path.isabs(path)

ReturnTrue ifpath is an absolute pathname. On Unix, that means itbegins with a slash, on Windows that it begins with a (back)slash after choppingoff a potential drive letter.

os.path.isfile(path)

ReturnTrue ifpath is an existing regular file. This follows symboliclinks, so bothislink() andisfile() can be true for the same path.

os.path.isdir(path)

ReturnTrue ifpath is an existing directory. This follows symboliclinks, so bothislink() andisdir() can be true for the same path.

os.path.islink(path)

ReturnTrue ifpath refers to a directory entry that is a symbolic link.AlwaysFalse if symbolic links are not supported by the Python runtime.

os.path.ismount(path)

ReturnTrue if pathnamepath is amount point: a point in afile system where a different file system has been mounted. On POSIX, thefunction checks whetherpath’s parent,path/.., is on a differentdevice thanpath, or whetherpath/.. andpath point to the samei-node on the same device — this should detect mount points for all Unixand POSIX variants. On Windows, a drive letter root and a share UNC arealways mount points, and for any other pathGetVolumePathName is calledto see if it is different from the input path.

New in version 3.4:Support for detecting non-root mount points on Windows.

os.path.join(path,*paths)

Join one or more path components intelligently. The return value is theconcatenation ofpath and any members of*paths with exactly onedirectory separator (os.sep) following each non-empty part except thelast, meaning that the result will only end in a separator if the lastpart is empty. If a component is an absolute path, all previouscomponents are thrown away and joining continues from the absolute pathcomponent.

On Windows, the drive letter is not reset when an absolute path component(e.g.,r'\foo') is encountered. If a component contains a driveletter, all previous components are thrown away and the drive letter isreset. Note that since there is a current directory for each drive,os.path.join("c:","foo") represents a path relative to the currentdirectory on driveC: (c:foo), notc:\foo.

os.path.normcase(path)

Normalize the case of a pathname. On Unix and Mac OS X, this returns thepath unchanged; on case-insensitive filesystems, it converts the path tolowercase. On Windows, it also converts forward slashes to backward slashes.Raise a TypeError if the type ofpath is notstr orbytes.

os.path.normpath(path)

Normalize a pathname by collapsing redundant separators and up-levelreferences so thatA//B,A/B/,A/./B andA/foo/../B allbecomeA/B. This string manipulation may change the meaning of a paththat contains symbolic links. On Windows, it converts forward slashes tobackward slashes. To normalize case, usenormcase().

os.path.realpath(path)

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

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

Return a relative filepath topath either from the current directory orfrom an optionalstart directory. This is a path computation: thefilesystem is not accessed to confirm the existence or nature ofpath orstart.

start defaults toos.curdir.

Availability: Unix, Windows.

os.path.samefile(path1,path2)

ReturnTrue if both pathname arguments refer to the same file or directory.This is determined by the device number and i-node number and raises anexception if anos.stat() call on either pathname fails.

Availability: Unix, Windows.

Changed in version 3.2:Added Windows support.

Changed in version 3.4:Windows now uses the same implementation as all other platforms.

os.path.sameopenfile(fp1,fp2)

ReturnTrue if the file descriptorsfp1 andfp2 refer to the same file.

Availability: Unix, Windows.

Changed in version 3.2:Added Windows support.

os.path.samestat(stat1,stat2)

ReturnTrue if the stat tuplesstat1 andstat2 refer to the same file.These structures may have been returned byos.fstat(),os.lstat(), oros.stat(). This function implements theunderlying comparison used bysamefile() andsameopenfile().

Availability: Unix, Windows.

Changed in version 3.4:Added Windows support.

os.path.split(path)

Split the pathnamepath into a pair,(head,tail) wheretail is thelast pathname component andhead is everything leading up to that. Thetail part will never contain a slash; ifpath ends in a slash,tailwill be empty. If there is no slash inpath,head will be empty. Ifpath is empty, bothhead andtail are empty. Trailing slashes arestripped fromhead unless it is the root (one or more slashes only). Inall cases,join(head,tail) returns a path to the same location aspath(but the strings may differ). Also see the functionsdirname() andbasename().

os.path.splitdrive(path)

Split the pathnamepath into a pair(drive,tail) wheredrive is eithera mount point or the empty string. On systems which do not use drivespecifications,drive will always be the empty string. In all cases,drive+tail will be the same aspath.

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

If the path contains a drive letter, drive will contain everythingup 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 nameand share, up to but not including the fourth separator.e.g.splitdrive("//host/computer/dir") returns("//host/computer","/dir")

os.path.splitext(path)

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

os.path.splitunc(path)

Deprecated since version 3.1:Usesplitdrive instead.

Split the pathnamepath into a pair(unc,rest) so thatunc is the UNCmount point (such asr'\\host\mount'), if present, andrest the rest ofthe path (such asr'\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 limitationsimposed by the file system).