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IoT.js-API-File-System.md

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Module: fs

Platform Support

The following shows fs module APIs available for each platform.

Linux
(Ubuntu)		 Raspbian
(Raspberry Pi)		 Nuttx
(STM32F4-Discovery)
fs.close O O O
fs.closeSync O O O
fs.open O O O
fs.openSync O O O
fs.read O O O
fs.readSync O O O
fs.readDir O O X
fs.readDirSync O O X
fs.readFile O O O
fs.readFileSync O O O
fs.rename O O O
fs.renameSync O O O
fs.stat O O O
fs.statSync O O O
fs.fstat O O O
fs.fstatSync O O O
fs.write O O O
fs.writeSync O O O
fs.writeFile O O O
fs.writeFileSync O O O
fs.unlink O O O
fs.unlinkSync O O O

※ On nuttx path should be passed with a form of absolute path.

Methods

fs.close(fd, callback)

  • fd: Int - file descriptor.
  • callback: Function(err)
  • err: Error

Closes the file of fd asynchronously.

fs.closeSync(fd)

  • fd: Int - file descriptor.

Closes the file of fd synchronously.

fs.open(path, flags[, mode], callback)

  • path: String - file path to be opened.
  • flags: String - open flags.
  • mode: Number, Default: 0666 - permission mode.
  • callback: Function(err, fd)
  • err: Error - Error object if there was something wrong, otherwise null.
  • fd: Number - file descriptor.

fs.openSync(path, flags[, mode])

  • path: String - file path to be opened.
  • flags: String - open flags.
  • mode: Number, Default: 0666 - permission mode.

fs.read(fd, buffer, offset, length, position, callback)

  • fd: Int - file descriptor.
  • buffer: Buffer - buffer that the data will be written to.
  • offset: Number - offset of the buffer where to start writing.
  • length: Number - number of bytes to read.
  • position: Number - specifying where to start read data from the file, if null, read from current position.
  • callback: Function(err, bytesRead, buffer)
  • err: Error
  • bytesRead: Number
  • buffer: Buffer

fs.readSync(fd, buffer, offset, length, position)

  • fd: Int - file descriptor.
  • buffer: Buffer - buffer that the data will be written to.
  • offset: Number - offset of the buffer where to start writing.
  • length: Number - number of bytes to read.
  • position: Number - specifying where to start read data from the file, if null, read from current position.

fs.readFile(path[, options], callback)

  • path: String - file path to be opened.
  • options: Object - options for the operation.
  • encoding: String, Default: null - encoding of the file.
  • flag: String, Default: r - file open flag.
  • callback: Function(err, data) - callback function.
  • err: Error
  • data: Buffer

Reads entire file asynchronously.

fs.readFileSync(path[, options])

  • path: String - file path to be opened.
  • options: Object - options for the operation.
  • encoding: String, Default: null - encoding of the file.
  • flag: String, Default: r - file open flag.

Reads entire file synchronously.

fs.rename(oldPath, newPath, callback)

  • oldPath: String - old file path
  • newPath: String - new file path
  • callback: Function(err) - callback function.
  • err: Error

Renames oldPath to newPath asynchronously.

fs.renameSync(oldPath, newPath)

  • oldPath: String - old file path
  • newPath: String - new file path

Renames oldPath to newPath synchronously.

fs.stat(path, callback)

  • path: String - file path to be stated
  • callback: Function(err, stat)` - callback function.
  • err: Error
  • stat: Object

fs.statSync(path)

  • path: String - file path to be stated

fs.fstat(fd, callback)

  • fd: Number - file descriptor to be stated
  • callback: Function(err, stat)` - callback function.
  • err: Error
  • stat: Object

fs.fstatSync(fd)

  • fd: Number - file descriptor to be stated

Class: fs.Stats

fs.Stats class is a object returned from fs.stat(),fs.fstat() and their synchronous counterparts.

Methods

stats.isDirectory()

Returns true if stated file is a directory

stats.isFile()

Returns true if stated file is a file

fs.write(fd, buffer, offset, length, position, callback)

  • fd: Int - file descriptor.
  • buffer: Buffer - buffer that the data will be written from.
  • offset: Number - offset of the buffer where from start reading.
  • length: Number - number of bytes to write.
  • position: Number - specifying where to start write data to the file, if null, read from current position.
  • callback: Function(err, bytesWrite)` - callback function.
  • err: Error
  • byteWrite: Int

fs.writeSync(fd, buffer, offset, length, position)

  • fd: Int - file descriptor.
  • buffer: Buffer - buffer that the data will be written from.
  • offset: Number - offset of the buffer where from start reading.
  • length: Number - number of bytes to write.
  • position: Number - specifying where to start write data to the file, if null, read from current position.

fs.writeFile(path, data, [, options], callback)

  • path: String - file path that the data will be written
  • data: Buffer - buffer that contains data
  • options: Object - options for the operation
  • callback: Function(err) - callback function
  • err: Error

Writes entire data to the file specified by path asynchronously.

fs.writeFileSync(path, data, [, options])

  • path: String - file path that the data will be written
  • data: Buffer - buffer that contains data
  • options: Object - options for the operation

Writes entire data to the file specified by path synchronously.

fs.unlink(path, callback)

  • path: String - file path to be removed
  • callback: Function(err)
  • err: Error

Removes the file specified by path asynchronously.

fs.unlinkSync(path)

  • path: String - file path to be removed

Removes the file specified by path synchronously.