Module fs

This module provides a file system API for the manipulation of paths, directories, files, links, and the construction of input and output streams. It follows the CommonJS Filesystem/A proposal.

Some file system manipulations use a wrapper around standard POSIX functions. Their functionality depends on the concrete file system and operating system. Others use the java.io package and work cross-platform.

Functions

Class Path

Instance Methods

Class Permissions

Instance Methods


Path ()

Path constructor. Path is a chainable shorthand for working with paths.


Path.prototype.from (target)

Return the relative path from the given source path to this path. Equivalent to fs.Path(fs.relative(source, this)).

Parameters

target

Path.prototype.join ()

Join a list of paths to this path.


Path.prototype.listPaths ()

Return the names of all files in this path, in lexically sorted order and wrapped in Path objects.


Path.prototype.resolve ()

Resolve against this path.


Path.prototype.to (target)

Return the relative path from this path to the given target path. Equivalent to fs.Path(fs.relative(this, target)).

Parameters

target

Path.prototype.toString ()


Path.prototype.valueOf ()

This is a non-standard extension, not part of CommonJS Filesystem/A.


Permissions (permissions, constructor)

The Permissions class describes the permissions associated with a file.

Parameters

Number|Object permissions a number or object representing the permissions.
constructor

Permissions.prototype.toNumber ()


Permissions.prototype.update (permissions)

Parameters

Number|Object permissions

absolute (path)

Make the given path absolute by resolving it against the current working directory.

Example

>> fs.absolute('foo/bar/test.txt');
'/Users/username/Desktop/working-directory/foo/bar/test.txt'

Parameters

path the path to resolve

Returns

String the absolute path

base (path, ext)

Return the basename of the given path. That is the path with any leading directory components removed. If specified, also remove a trailing extension.

Example

>> fs.base('/a/b/c/foosomeext', 'someext');
'foo'

Parameters

String path the full path
String ext an optional extension to remove

Returns

String the basename

canonical (path)

Returns the canonical path to a given abstract path. Canonical paths are both absolute and intrinsic, such that all paths that refer to a given file (whether it exists or not) have the same corresponding canonical path.

Parameters

String path a file path

Returns

String the canonical path

changeGroup (path, group)

Changes the group of the specified file. This function wraps the POSIX chown() function. Supports group name string as well as gid number input.

Parameters

String path
String|Number group group name string or gid number

See


changeOwner (path, owner)

Changes the owner of the specified file. This function wraps the POSIX chown() function. Supports user name string as well as uid number input.

Parameters

String path
String|Number owner the user name string or uid number

See


changePermissions (path, permissions)

Changes the permissions of the specified file. This function wraps the POSIX chmod() function.

Parameters

String path
Number|Object permissions

See


changeWorkingDirectory (path)

Set the current working directory to path.

Parameters

String path the new working directory

copy (from, to)

Read data from one file and write it into another using binary mode.

Example

// Copies file from a temporary upload directory into /var/www
fs.copy('/tmp/uploads/fileA.txt', '/var/www/fileA.txt');

Parameters

String from original file
String to copy to create

copyTree (from, to)

Copy files from a source path to a target path. Files of the below the source path are copied to the corresponding locations relative to the target path, symbolic links to directories are copied but not traversed into.

Example

Before:
└── foo
    ├── bar
    │   └── example.m4a
    └── baz

// Copy foo
fs.copyTree('./foo', './foo2');

After:
├── foo
│   ├── bar
│   │   └── example.m4a
│   └── baz
└── foo2
    ├── bar
    │   └── example.m4a
    └── baz

Parameters

String from the original tree
String to the destination for the copy

directory (path)

Return the dirname of the given path. That is the path with any trailing non-directory component removed.

Example

>> fs.directory('/Users/username/Desktop/example/test.txt');
'/Users/username/Desktop/example'

Parameters

String path

Returns

String the parent directory path

exists (path)

Return true if the file denoted by path exists, false otherwise.

Parameters

String path the file path.

extension (path)

Return the extension of a given path. That is everything after the last dot in the basename of the given path, including the last dot. Returns an empty string if no valid extension exists.

Example

>> fs.extension('test.txt');
'.txt'

Parameters

String path

Returns

String the file's extension

group (path)

Parameters

String path

hardLink (source, target)

Creates a hard link at the target path that refers to the source path. The concrete implementation depends on the file system and the operating system.

This function wraps the POSIX link() function, which may not work on Microsoft Windows platforms.

Parameters

String source the source file
String target the target file

See


isAbsolute (path)

Check whether the given pathname is absolute. This is a non-standard extension, not part of CommonJS Filesystem/A.

Example

>> fs.isAbsolute('../../');
false
>> fs.isAbsolute('/Users/username/Desktop/example.txt');
true

Parameters

path the path to check

Returns

Boolean true if path is absolute, false if not

isDirectory (path)

Returns true if the file specified by path exists and is a directory.

Parameters

String path the file path

Returns

Boolean whether the file exists and is a directory

isFile (path)

Returns true if the file specified by path exists and is a regular file.

Parameters

String path the file path

Returns

Boolean whether the file exists and is a file

isLink (path)

Return true if target file is a symbolic link, false otherwise.

This function wraps the POSIX lstat() function to get the symbolic link status.

Parameters

String path the file path

Returns

Boolean true if the given file exists and is a symbolic link

See


isReadable (path)

Returns true if the file specified by path exists and can be opened for reading.

Parameters

String path the file path

Returns

Boolean whether the file exists and is readable

isRelative (path)

Check whether the given pathname is relative (i.e. not absolute). This is a non-standard extension, not part of CommonJS Filesystem/A.

Parameters

path the path to check

Returns

Boolean true if path is relative, false if not

isWritable (path)

Returns true if the file specified by path exists and can be opened for writing.

Parameters

String path the file path

Returns

Boolean whether the file exists and is writable

iterate (path)

Returns a generator that produces the file names of a directory.

Parameters

String path a directory path

join ()

Join a list of paths using the local file system's path separator. The result is not normalized, so join("..", "foo") returns "../foo".

See


lastModified (path)

Returns the time a file was last modified as a Date object.

Parameters

String path the file path

Returns

Date the date the file was last modified

list (path)

Returns an array with all the names of files contained in the direcory path.

Parameters

String path the directory path

Returns

Array a list of file names

listDirectoryTree (path)

Return an array with all directories below (and including) the given path, as discovered by depth-first traversal. Entries are in lexically sorted order within directories. Symbolic links to directories are not traversed into.

Example

// File system tree of the current working directory:
.
└── foo
    └── bar
        └── baz

fs.listDirectoryTree('.');
// returned array:
[ '', 'foo', 'foo/bar', 'foo/bar/baz' ]

Parameters

path the path to discover

Returns

Array array of strings with all directories lexically sorted

listTree (path)

Return an array with all paths (files, directories, etc.) below (and including) the given path, as discovered by depth-first traversal. Entries are in lexically sorted order within directories. Symbolic links to directories are returned but not traversed into.

Example

// File system tree of the current working directory:
.
├── foo
│   └── bar
│       └── baz
├── musicfile.m4a
└── test.txt

fs.listTree('.');
// returned array:
['', 'foo', 'foo/bar', 'foo/bar/baz', 'musicfile.m4a', 'test.txt']

Parameters

path the path to list

Returns

Array array of strings with all discovered paths

makeDirectory (path, permissions)

Create a single directory specified by path. If the directory cannot be created for any reason an error is thrown. This includes if the parent directories of path are not present. If a permissions argument is passed to this function it is used to create a Permissions instance which is applied to the given path during directory creation.

This function wraps the POSIX mkdir() function.

Parameters

String path the file path
Number|Object permissions optional permissions

See


makeTree (path)

Create the directory specified by path including any missing parent directories.

Example

Before:
└── foo

fs.makeTree('foo/bar/baz/');

After:
└── foo
   └── bar
      └── baz

Parameters

path the path of the tree to create

move (source, target)

Move a file from source to target.

Example

// Moves file from a temporary upload directory into /var/www
fs.move('/tmp/uploads/fileA.txt', '/var/www/fileA.txt');

Parameters

String source the source path
String target the target path

Throws

Error

normal (path)

Normalize a path by removing '.' and simplifying '..' components, wherever possible.

Example

>> fs.normal('../redundant/../foo/./bar.txt');
'../foo/bar.txt'

Parameters

path

Returns

String the normalized path

open (path, options)

Open the file corresponding to path for reading or writing, depending on the options argument. Returns a binary stream or a text stream.

The options argument may contain the following properties:

  • read (boolean) open the file in read-only mode.
  • write (boolean) open the file in write mode starting at the beginning of the file.
  • append (boolean) open the file in write mode starting at the end of the file.
  • binary (boolean) open the file in binary mode.
  • charset (string) open the file in text mode using the given encoding. Defaults to UTF-8.

Instead of an options object, a string with the following modes can be provided:

  • r (string) equivalent to read-only
  • w (string) equivalent to write
  • a (string) equivalent to append
  • b (string) equivalent to binary

So an options object { read: true, binary: true } and the mode string 'rb' are functionally equivalent.

Example

// Opens a m4a file in binary mode
var m4aStream = fs.open('music.m4a', {
   binary: true,
   read: true
});

// The equivalent call with options as string
var m4aStream = fs.open('music.m4a', 'br');

// Opens a text file
var textStream = fs.open('example.txt', { read: true });

// The equivalent call with options as string
var textStream = fs.open('example.txt', 'r');

Parameters

String path the file path
Object|String options options as object properties or as mode string

Returns

Stream|TextStream a Stream object in binary mode, otherwise a TextStream

openRaw (path, options, permissions)

Opens the file corresponding to path for reading or writing in binary mode. This function supports the same options as open() except for binary and charset.

Parameters

String path the file path
Object options options
Object permissions not yet supported

Returns

Stream

See


owner (path)

Parameters

String path

path ()

A shorthand for creating a new Path without the new keyword.


permissions (path)

Parameters

String path

read (path, options)

Read the content of the file corresponding to path. Returns a String or ByteString object depending on the options argument. This function supports the same options as open().

Parameters

String path the file path
Object options optional options

Returns

String|Binary the content of the file

readLink (path)

Returns the immediate target of the symbolic link at the given path.

This function wraps the POSIX readlink() function, which may not work on Microsoft Windows platforms.

Parameters

String path a file path

See


relative (source, target)

Establish the relative path that links source to target by strictly traversing up ('..') to find a common ancestor of both paths. If the target is omitted, returns the path to the source from the current working directory.

Example

>> fs.relative('foo/bar/', 'foo/baz/');
'../baz/'
>> fs.relative('foo/bar/', 'foo/bar/baz/');
'baz/'

Parameters

String source
String target

Returns

String the path needed to change from source to target

remove (path)

Remove a file at the given path. Throws an error if path is not a file or a symbolic link to a file.

Parameters

String path the path of the file to remove.

Throws

Error if path is not a file or could not be removed.

removeDirectory (path)

Remove a file or directory identified by path. Throws an error if path is a directory and not empty.

Parameters

String path the directory path

Throws

Error if the file or directory could not be removed.

removeTree (path)

Remove the element pointed to by the given path. If path points to a directory, all members of the directory are removed recursively.

Example

// File system tree of the current working directory:
├── foo
│   └── bar
│       └── baz
├── musicfile.m4a
└── test.txt

fs.removeTree('foo');

After:
├── musicfile.m4a
└── test.txt

Parameters

path the element to delete recursively

resolve (paths...)

Join a list of paths by starting at an empty location and iteratively "walking" to each path given. Correctly takes into account both relative and absolute paths.

Example

>> fs.resolve('../.././foo/file.txt', 'bar/baz/', 'test.txt');
'../../foo/bar/baz/test.txt'

Parameters

paths... the paths to resolve

Returns

String the joined path

same (pathA, pathB)

Returns whether two paths refer to the same storage (file or directory), either by virtue of symbolic or hard links, such that modifying one would modify the other.

This function uses the POSIX stat() function to compare two files or links.

Parameters

String pathA the first path
String pathB the second path

Returns

Boolean true if identical, otherwise false

See


sameFilesystem (pathA, pathB)

Returns whether two paths refer to an entity of the same file system.

This function uses the POSIX stat() function to compare two paths by checking if the associated devices are identical.

Parameters

String pathA the first path
String pathB the second path

Returns

Boolean true if same file system, otherwise false

See


size (path)

Returns the size of a file in bytes, or throws an exception if the path does not correspond to an accessible path, or is not a regular file or a link.

Parameters

String path the file path

Returns

Number the file size in bytes

Throws

Error if path is not a file

split (path)

Split a given path into an array of path components.

Example

>> fs.split('/Users/someuser/Desktop/subdir/test.txt');
[ '', 'Users', 'someuser', 'Desktop', 'subdir', 'test.txt' ]

Parameters

String path

Returns

Array the path components

symbolicLink (source, target)

Creates a symbolic link at the target path that refers to the source path. The concrete implementation depends on the file system and the operating system.

This function wraps the POSIX symlink() function, which may not work on Microsoft Windows platforms.

Parameters

String source the source file
String target the target link

See


touch (path, mtime)

Sets the modification time of a file or directory at a given path to a specified time, or the current time. Creates an empty file at the given path if no file or directory exists, using the default permissions.

Parameters

String path the file path
Date mtime optional date

workingDirectory ()

Return the path name of the current working directory.

Returns

String the current working directory

write (path, content, options)

Open, write, flush, and close a file, writing the given content. If content is a ByteArray or ByteString from the binary module, binary mode is implied.

Parameters

String path
ByteArray|ByteString|String content
Object options

See

ByteArray or ByteString for binary data