createDirectory dir creates a new directory dir which is initially empty, or as near to empty as the operating system allows.

The operation may fail with:

• isPermissionError / PermissionDenied The process has insufficient privileges to perform the operation. [EROFS, EACCES]
• isAlreadyExistsError / AlreadyExists The operand refers to a directory that already exists. [EEXIST]
• HardwareFault A physical I/O error has occurred. [EIO]
• InvalidArgument The operand is not a valid directory name. [ENAMETOOLONG, ELOOP]
• NoSuchThing There is no path to the directory. [ENOENT, ENOTDIR]
• ResourceExhausted Insufficient resources (virtual memory, process file descriptors, physical disk space, etc.) are available to perform the operation. [EDQUOT, ENOSPC, ENOMEM, EMLINK]
• InappropriateType The path refers to an existing non-directory object. [EEXIST]

createDirectoryIfMissing parents dir creates a new directory dir if it doesn't exist. If the first argument is True the function will also create all parent directories if they are missing.

removeDirectory dir removes an existing directory dir. The implementation may specify additional constraints which must be satisfied before a directory can be removed (e.g. the directory has to be empty, or may not be in use by other processes). It is not legal for an implementation to partially remove a directory unless the entire directory is removed. A conformant implementation need not support directory removal in all situations (e.g. removal of the root directory).

The operation may fail with:

• HardwareFault A physical I/O error has occurred. [EIO]
• InvalidArgument The operand is not a valid directory name. [ENAMETOOLONG, ELOOP]
• isDoesNotExistError / NoSuchThing The directory does not exist. [ENOENT, ENOTDIR]
• isPermissionError / PermissionDenied The process has insufficient privileges to perform the operation. [EROFS, EACCES, EPERM]
• UnsatisfiedConstraints Implementation-dependent constraints are not satisfied. [EBUSY, ENOTEMPTY, EEXIST]
• UnsupportedOperation The implementation does not support removal in this situation. [EINVAL]
• InappropriateType The operand refers to an existing non-directory object. [ENOTDIR]

removeDirectoryRecursive dir removes an existing directory dir together with its contents and subdirectories. Within this directory, symbolic links are removed without affecting their targets.

On Windows, the operation fails if dir is a directory symbolic link.

renameDirectory old new changes the name of an existing directory from old to new. If the new directory already exists, it is atomically replaced by the old directory. If the new directory is neither the old directory nor an alias of the old directory, it is removed as if by removeDirectory. A conformant implementation need not support renaming directories in all situations (e.g. renaming to an existing directory, or across different physical devices), but the constraints must be documented.

On Win32 platforms, renameDirectory fails if the new directory already exists.

The operation may fail with:

• HardwareFault A physical I/O error has occurred. [EIO]
• InvalidArgument Either operand is not a valid directory name. [ENAMETOOLONG, ELOOP]
• isDoesNotExistError / NoSuchThing The original directory does not exist, or there is no path to the target. [ENOENT, ENOTDIR]
• isPermissionError / PermissionDenied The process has insufficient privileges to perform the operation. [EROFS, EACCES, EPERM]
• ResourceExhausted Insufficient resources are available to perform the operation. [EDQUOT, ENOSPC, ENOMEM, EMLINK]
• UnsatisfiedConstraints Implementation-dependent constraints are not satisfied. [EBUSY, ENOTEMPTY, EEXIST]
• UnsupportedOperation The implementation does not support renaming in this situation. [EINVAL, EXDEV]
• InappropriateType Either path refers to an existing non-directory object. [ENOTDIR, EISDIR]

Similar to listDirectory, but always includes the special entries (. and ..). (This applies to Windows as well.)

The operation may fail with the same exceptions as listDirectory.

If the operating system has a notion of current directories, getCurrentDirectory returns an absolute path to the current directory of the calling process.

The operation may fail with:

• HardwareFault A physical I/O error has occurred. [EIO]
• isDoesNotExistError / NoSuchThing There is no path referring to the current directory. [EPERM, ENOENT, ESTALE...]
• isPermissionError / PermissionDenied The process has insufficient privileges to perform the operation. [EACCES]
• ResourceExhausted Insufficient resources are available to perform the operation.
• UnsupportedOperation The operating system has no notion of current directory.

Change the working directory to the given path.

In a multithreaded program, the current working directory is a global state shared among all threads of the process. Therefore, when performing filesystem operations from multiple threads, it is highly recommended to use absolute rather than relative paths (see: makeAbsolute).

The operation may fail with:

• HardwareFault A physical I/O error has occurred. [EIO]
• InvalidArgument The operand is not a valid directory name. [ENAMETOOLONG, ELOOP]
• isDoesNotExistError or NoSuchThing The directory does not exist. [ENOENT, ENOTDIR]
• isPermissionError or PermissionDenied The process has insufficient privileges to perform the operation. [EACCES]
• UnsupportedOperation The operating system has no notion of current working directory, or the working directory cannot be dynamically changed.
• InappropriateType The path refers to an existing non-directory object. [ENOTDIR]

Returns the current user's home directory.

The directory returned is expected to be writable by the current user, but note that it isn't generally considered good practice to store application-specific data here; use getAppUserDataDirectory instead.

On Unix, getHomeDirectory returns the value of the HOME environment variable. On Windows, the system is queried for a suitable path; a typical path might be C:Documents And Settingsuser.

The operation may fail with:

• UnsupportedOperation The operating system has no notion of home directory.
• isDoesNotExistError The home directory for the current user does not exist, or cannot be found.

Returns the current user's home directory from the HOME environment variable.

Returns the pathname of a directory in which application-specific data for the current user can be stored. The result of getAppUserDataDirectory for a given application is specific to the current user.

The argument should be the name of the application, which will be used to construct the pathname (so avoid using unusual characters that might result in an invalid pathname).

Note: the directory may not actually exist, and may need to be created first. It is expected that the parent directory exists and is writable.

On Unix, this function returns $HOME/.appName. On Windows, a typical path might be

C:/Documents And Settings/user/Application Data/appName

The operation may fail with:

• UnsupportedOperation The operating system has no notion of application-specific data directory.
• isDoesNotExistError The home directory for the current user does not exist, or cannot be found.

Returns the current user's document directory.

The directory returned is expected to be writable by the current user, but note that it isn't generally considered good practice to store application-specific data here; use getAppUserDataDirectory instead.

On Unix, getUserDocumentsDirectory returns the value of the HOME environment variable. On Windows, the system is queried for a suitable path; a typical path might be C:/Documents and Settings/user/My Documents.

The operation may fail with:

• UnsupportedOperation The operating system has no notion of document directory.
• isDoesNotExistError The document directory for the current user does not exist, or cannot be found.

Returns the current directory for temporary files.

On Unix, getTemporaryDirectory returns the value of the TMPDIR environment variable or "/tmp" if the variable isn't defined. On Windows, the function checks for the existence of environment variables in the following order and uses the first path found:

• TMP environment variable.
• TEMP environment variable.
• USERPROFILE environment variable.
• The Windows directory

The operation may fail with:

• UnsupportedOperation The operating system has no notion of temporary directory.

The function doesn't verify whether the path exists.

removeFile file removes the directory entry for an existing file file, where file is not itself a directory. The implementation may specify additional constraints which must be satisfied before a file can be removed (e.g. the file may not be in use by other processes).

The operation may fail with:

• HardwareFault A physical I/O error has occurred. [EIO]
• InvalidArgument The operand is not a valid file name. [ENAMETOOLONG, ELOOP]
• isDoesNotExistError / NoSuchThing The file does not exist. [ENOENT, ENOTDIR]
• isPermissionError / PermissionDenied The process has insufficient privileges to perform the operation. [EROFS, EACCES, EPERM]
• UnsatisfiedConstraints Implementation-dependent constraints are not satisfied. [EBUSY]
• InappropriateType The operand refers to an existing directory. [EPERM, EINVAL]

renameFile old new changes the name of an existing file system object from old to new. If the new object already exists, it is atomically replaced by the old object. Neither path may refer to an existing directory. A conformant implementation need not support renaming files in all situations (e.g. renaming across different physical devices), but the constraints must be documented.

The operation may fail with:

• HardwareFault A physical I/O error has occurred. [EIO]
• InvalidArgument Either operand is not a valid file name. [ENAMETOOLONG, ELOOP]
• isDoesNotExistError / NoSuchThing The original file does not exist, or there is no path to the target. [ENOENT, ENOTDIR]
• isPermissionError / PermissionDenied The process has insufficient privileges to perform the operation. [EROFS, EACCES, EPERM]
• ResourceExhausted Insufficient resources are available to perform the operation. [EDQUOT, ENOSPC, ENOMEM, EMLINK]
• UnsatisfiedConstraints Implementation-dependent constraints are not satisfied. [EBUSY]
• UnsupportedOperation The implementation does not support renaming in this situation. [EXDEV]
• InappropriateType Either path refers to an existing directory. [ENOTDIR, EISDIR, EINVAL, EEXIST, ENOTEMPTY]

Copy a file with its permissions. If the destination file already exists, it is replaced atomically. Neither path may refer to an existing directory. No exceptions are thrown if the permissions could not be copied.

Make a path absolute and remove as many indirections from it as possible. Indirections include the two special directories . and .., as well as any Unix symbolic links. The input path does not have to point to an existing file or directory.

Note: if you only need an absolute path, use makeAbsolute instead. Most programs should not worry about whether a path contains symbolic links.

Since symbolic links and the special parent directory (..) are dependent on the state of the existing filesystem, the function can only make a conservative attempt by removing symbolic links and .. from the longest prefix of the path that still points to an existing file or directory. If the input path points to an existing file or directory, then the output path shall also point to the same file or directory, provided that the relevant parts of the filesystem have not changed in the meantime (the function is not atomic).

Despite the name, the function does not guarantee canonicity of the returned path due to the presence of hard links, mount points, etc.

Similar to normalise, passing an empty path is equivalent to passing the current directory. The function preserves the presence or absence of the trailing path separator unless the path refers to the root directory /.

Known bug(s): on Windows, the function does not resolve symbolic links.

Changes since 1.2.3.0: The function has been altered to be more robust and has the same exception behavior as makeAbsolute.

The operation doesFileExist returns True if the argument file exists and is not a directory, and False otherwise.

The operation doesDirectoryExist returns True if the argument file exists and is either a directory or a symbolic link to a directory, and False otherwise.

The getPermissions operation returns the permissions for the file or directory.

The operation may fail with:

• isPermissionError if the user is not permitted to access the permissions; or
• isDoesNotExistError if the file or directory does not exist.

The setPermissions operation sets the permissions for the file or directory.

The operation may fail with:

• isPermissionError if the user is not permitted to set the permissions; or
• isDoesNotExistError if the file or directory does not exist.

This function copy the permission of the first file to the second.

The getCreationTime operation returns the UTC time at which the file or directory was created. The time is only available on Windows.

The getChangeTime operation returns the UTC time at which the file or directory was changed. The time is only available on Unix and Mac. Note that Unix's rename() does not change ctime but MacOS's rename() does.

The getModificationTime operation returns the UTC time at which the file or directory was last modified.

The operation may fail with:

• isPermissionError if the user is not permitted to access the modification time; or
• isDoesNotExistError if the file or directory does not exist.

The getModificationTime operation returns the UTC time at which the file or directory was last accessed.

Getting the size of the file.

This function tells whether or not a file/directory is symbolic link.

This function returns the link counter of a file/directory.

This function returns whether or not a directory has sub-directories.

File and directory names are values of type String, whose precise meaning is operating system dependent. Files can be opened, yielding a handle which can then be used to operate on the contents of that file.

The character that separates directories.

pathSeparator ==  '/'
isPathSeparator pathSeparator

The list of all possible separators.

Windows: pathSeparators == ['\\', '/']
Posix:   pathSeparators == ['/']
pathSeparator `elem` pathSeparators

Rather than using (== pathSeparator), use this. Test if something is a path separator.

isPathSeparator a == (a `elem` pathSeparators)

File extension character

extSeparator == '.'

Is the character an extension character?

isExtSeparator a == (a == extSeparator)

Split on the extension. addExtension is the inverse.

uncurry (++) (splitExtension x) == x
uncurry addExtension (splitExtension x) == x
splitExtension "file.txt" == ("file",".txt")
splitExtension "file" == ("file","")
splitExtension "file/file.txt" == ("file/file",".txt")
splitExtension "file.txt/boris" == ("file.txt/boris","")
splitExtension "file.txt/boris.ext" == ("file.txt/boris",".ext")
splitExtension "file/path.txt.bob.fred" == ("file/path.txt.bob",".fred")
splitExtension "file/path.txt/" == ("file/path.txt/","")

Get the extension of a file, returns "" for no extension, .ext otherwise.

takeExtension x == snd (splitExtension x)
Valid x => takeExtension (addExtension x "ext") == ".ext"
Valid x => takeExtension (replaceExtension x "ext") == ".ext"

Set the extension of a file, overwriting one if already present.

replaceExtension "file.txt" ".bob" == "file.bob"
replaceExtension "file.txt" "bob" == "file.bob"
replaceExtension "file" ".bob" == "file.bob"
replaceExtension "file.txt" "" == "file"
replaceExtension "file.fred.bob" "txt" == "file.fred.txt"

Remove last extension, and the "." preceding it.

dropExtension x == fst (splitExtension x)

Add an extension, even if there is already one there. E.g. addExtension "foo.txt" "bat" -> "foo.txt.bat".

addExtension "file.txt" "bib" == "file.txt.bib"
addExtension "file." ".bib" == "file..bib"
addExtension "file" ".bib" == "file.bib"
addExtension "/" "x" == "/.x"
Valid x => takeFileName (addExtension (addTrailingPathSeparator x) "ext") == ".ext"
Windows: addExtension "\\\\share" ".txt" == "\\\\share\\.txt"

Does the given filename have an extension?

null (takeExtension x) == not (hasExtension x)

Alias to addExtension, for people who like that sort of thing.

Split on all extensions

splitExtensions "file.tar.gz" == ("file",".tar.gz")

Drop all extensions

not $ hasExtension (dropExtensions x)

Get all extensions

takeExtensions "file.tar.gz" == ".tar.gz"

Split a path into a drive and a path. On Unix, / is a Drive.

uncurry (++) (splitDrive x) == x
Windows: splitDrive "file" == ("","file")
Windows: splitDrive "c:/file" == ("c:/","file")
Windows: splitDrive "\\\\shared\\test" == ("\\\\shared\\","test")
Windows: splitDrive "\\\\shared" == ("\\\\shared","")
Windows: splitDrive "\\\\?\\UNC\\shared\\file" == ("\\\\?\\UNC\\shared\\","file")
Windows: splitDrive "\\\\?\\UNCshared\\file" == ("\\\\?\\","UNCshared\\file")
Windows: splitDrive "\\\\?\\d:\\file" == ("\\\\?\\d:\\","file")
Windows: splitDrive "/d" == ("","/d") -- xxx
Posix:   splitDrive "/test" == ("/","test") -- xxx
Posix:   splitDrive "//test" == ("//","test")
Posix:   splitDrive "test/file" == ("","test/file")
Posix:   splitDrive "file" == ("","file")

Join a drive and the rest of the path.

         uncurry joinDrive (splitDrive x) == x
Windows: joinDrive "C:" "foo" == "C:foo"
Windows: joinDrive "C:/" "bar" == "C:/bar"
Windows: joinDrive "\\\\share" "foo" == "\\\\share/foo" -- xxx
Windows: joinDrive "/:" "foo" == "/:/foo" -- xxx

Get the drive from a filepath.

takeDrive x == fst (splitDrive x)

Does a path have a drive.

not (hasDrive x) == null (takeDrive x)

Delete the drive, if it exists.

dropDrive x == snd (splitDrive x)

Is an element a drive

Split a filename into directory and file. combine is the inverse.

uncurry (++) (splitFileName x) == x
Valid x => uncurry combine (splitFileName x) == x
splitFileName "file/bob.txt" == ("file/", "bob.txt")
splitFileName "file/" == ("file/", "")
splitFileName "bob" == ("", "bob")
Posix:   splitFileName "/" == ("/","")
Windows: splitFileName "c:" == ("c:","")

Get the file name.

takeFileName "test/" == ""
takeFileName x `isSuffixOf` x
takeFileName x == snd (splitFileName x)
Valid x => takeFileName (replaceFileName x "fred") == "fred"
Valid x => takeFileName (x </> "fred") == "fred"
Valid x => isRelative (takeFileName x)

Set the filename.

Valid x => replaceFileName x (takeFileName x) == x

Drop the filename.

dropFileName x == fst (splitFileName x)

Get the base name, without an extension or path.

takeBaseName "file/test.txt" == "test"
takeBaseName "dave.ext" == "dave"
takeBaseName "" == ""
takeBaseName "test" == "test"
takeBaseName (addTrailingPathSeparator x) == ""
takeBaseName "file/file.tar.gz" == "file.tar"

Set the base name.

replaceBaseName "file/test.txt" "bob" == "file/bob.txt"
replaceBaseName "fred" "bill" == "bill"
replaceBaseName "/dave/fred/bob.gz.tar" "new" == "/dave/fred/new.tar"
replaceBaseName x (takeBaseName x) == x

Get the directory name, move up one level.

          takeDirectory x `isPrefixOf` x
          takeDirectory "foo" == ""
          takeDirectory "/foo/bar/baz" == "/foo/bar"
          takeDirectory "/foo/bar/baz/" == "/foo/bar/baz"
          takeDirectory "foo/bar/baz" == "foo/bar"
Windows:  takeDirectory "foo\\bar\\\\" == "foo\\bar" -- xxx
Windows:  takeDirectory "C:/" == "C:/"

Set the directory, keeping the filename the same.

replaceDirectory x (takeDirectory x) `equalFilePath` x

Combine two paths, if the second path isAbsolute, then it returns the second.

Valid x => combine (takeDirectory x) (takeFileName x) `equalFilePath` x
combine "/" "test" == "/test"
combine "home" "bob" == "home/bob"

A nice alias for combine.

Split a path by the directory separator.

concat (splitPath x) == x
splitPath "test//item/" == ["test//","item/"]
splitPath "test/item/file" == ["test/","item/","file"]
splitPath "" == []
Windows: splitPath "c:/test/path" == ["c:/","test/","path"]
Posix:   splitPath "/file/test" == ["/","file/","test"]

Join path elements back together.

Valid x => joinPath (splitPath x) == x
joinPath [] == ""
Posix: joinPath ["test","file","path"] == "test/file/path"

Just as splitPath, but don't add the trailing slashes to each element.

splitDirectories "test/file" == ["test","file"]
splitDirectories "/test/file" == ["/","test","file"]
Valid x => joinPath (splitDirectories x) `equalFilePath` x
splitDirectories "" == []

Is an item either a directory or the last character a path separator?

hasTrailingPathSeparator "test" == False
hasTrailingPathSeparator "test/" == True

Add a trailing file path separator if one is not already present.

hasTrailingPathSeparator (addTrailingPathSeparator x)
hasTrailingPathSeparator x ==> addTrailingPathSeparator x == x
addTrailingPathSeparator "test/rest" == "test/rest/"

Remove any trailing path separators

dropTrailingPathSeparator "file/test/" == "file/test"
not (hasTrailingPathSeparator (dropTrailingPathSeparator x)) || isDrive x
dropTrailingPathSeparator "/" == "/"

Normalise a file

• // outside of the drive can be made blank
• / -> pathSeparator
• ./ -> ""

Posix:   normalise "/file/\\test////" == "/file/\\test/"
Posix:   normalise "/file/./test" == "/file/test"
Posix:   normalise "/test/file/../bob/fred/" == "/test/file/../bob/fred/"
Posix:   normalise "../bob/fred/" == "../bob/fred/"
Posix:   normalise "./bob/fred/" == "bob/fred/"
Windows: normalise "c:\\file/bob\\" == "C:/file/bob/"
Windows: normalise "c:/" == "C:/"
Windows: normalise "\\\\server\\test" == "\\\\server\\test" -- xxx
Windows: normalise "." == "."
Posix:   normalise "./" == "./"

Equality of two FilePaths. If you call System.Directory.canonicalizePath first this has a much better chance of working. Note that this doesn't follow symlinks or DOSNAM~1s.

         x == y ==> equalFilePath x y
         normalise x == normalise y ==> equalFilePath x y
Posix:   equalFilePath "foo" "foo/"
Posix:   not (equalFilePath "foo" "/foo")
Posix:   not (equalFilePath "foo" "FOO")
Windows: equalFilePath "foo" "FOO"

Contract a filename, based on a relative path.

There is no corresponding makeAbsolute function, instead use System.Directory.canonicalizePath which has the same effect.

         Valid y => equalFilePath x y || (isRelative x && makeRelative y x == x) || equalFilePath (y </> makeRelative y x) x
         makeRelative x x == "."
         null y || equalFilePath (makeRelative x (x </> y)) y || null (takeFileName x)
Windows: makeRelative "C:/Home" "c:/home/bob" == "bob"
Windows: makeRelative "C:/Home" "D:/Home/Bob" == "D:/Home/Bob"
Windows: makeRelative "C:/Home" "C:Home/Bob" == "C:Home/Bob"
Windows: makeRelative "/Home" "/home/bob" == "bob"
Posix:   makeRelative "/Home" "/home/bob" == "/home/bob"
Posix:   makeRelative "/home/" "/home/bob/foo/bar" == "bob/foo/bar"
Posix:   makeRelative "/fred" "bob" == "bob"
Posix:   makeRelative "/file/test" "/file/test/fred" == "fred"
Posix:   makeRelative "/file/test" "/file/test/fred/" == "fred/"
Posix:   makeRelative "some/path" "some/path/a/b/c" == "a/b/c"

Is a path relative, or is it fixed to the root?

Windows: isRelative "path\\test" == True
Windows: isRelative "c:\\test" == False
Windows: isRelative "c:test" == True
Windows: isRelative "c:" == True
Windows: isRelative "\\\\foo" == False
Windows: isRelative "/foo" == True
Posix:   isRelative "test/path" == True
Posix:   isRelative "/test" == False

not . isRelative

isAbsolute x == not (isRelative x)