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NodeJs version: 4.4.4

Fs

The file system module is a collection that encapsulates the standard POSIX file Imax O operations. The methods in the Node.js file system (fs module) module are available in both asynchronous and synchronous versions.

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Create a readable stream and a write stream. Through the pipeline pipe.

Var fileReadStream = fs.createReadStream (sourcePath); var fileWriteStream = fs.createWriteStream (targetPath); fileReadStream.pipe (fileWriteStream); / / listen to the shutdown event to learn that the execution is complete fileWriteStream.on ('close', function () {console.log (' mobile successful!');}) read the file (fs.readFile)

Definition: fs.readFile (filename [, options], callback)

Parameters:

Filename: {String} file name / file path

Options: {Object} optional parameters

Encoding: {String | Null} default = null encoding method

Flag: {String} default ='r' file opening behavior (writable, readable, etc.)

Callback: {Function}

Var fs = require ('fs'); / / read the file fs.readFile ('.. / lianxi/child_process.js', {encoding:'utf-8', flag:'r'}, function (err,data) {if (err) throw err; console.log (data);})

If you do not set the encoding to read the file here, the read file will be returned in the form of buffer.

When set to utf-8, the string is returned. It is as follows:

Var child_process = require ('child_process');...

Write file (fs.writeFile)

Definition: fs.writeFile (filename, data [, options], callback)

Parameters:

Filename: {String}

Data: {String | Buffer}

Options: {Object}

Encoding: {String | Null} default = 'utf8'

Mode: {Number} default = 438 (aka 0666 in Octal)

Flag: {String} default ='w'

Callback {Function}

/ / write the file fs.writeFile ('.. / lianxi/child_process.js',' [zqz] data string or buffer', {encoding:'utf8', mode:438, flag:'w'}, function (err) {})

Note: write the file asynchronously and replace it if the file already exists.

Open File (fs.open)

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

Parameters:

Path: file / file path

Flags: the act of opening a file

Mode: sets the file mode (permissions). The default permission for file creation is 0666 (readable and writable).

Callback: callback function

/ / Open the file fs.open ('.. / lianxi/child_process.js','r+',0666,function (err,data) {}) to add data (fs.appendFile) to the file

Definition: fs.appendFile (filename, data [, options], callback)

Parameters:

Filename: {String}

Data: {String | Buffer}

Options: {Object}

Encoding {String | Null} default = 'utf8'

Mode {Number} default = 438 (aka 0666 in Octal)

Flag {String} default ='a'

Callback {Function}

/ / add data fs.appendFile ('.. / lianxi/child_process.js', 'asynchronously added string or buffer', {encoding:'utf8', mode:438, flag:'a'}, function (err) {}) to the file

Note: add data to the file asynchronously, and if the file does not exist, a file will be created.

Delete a file (fs.unlink)

Definition: fs.unlink (path, callback)

Var fs = require ('fs'); fs.unlink ('. / err index. tml) {if (err) throw err; console.log ('success'}) create the file (fs.open)

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

You can also use fs.open to create files.

Fs.open ("test.txt", "w", function (err) {}); delete folder (fs.rmdir)

Definition: fs.rmdir (path, callback)

Fs.rmdir ('. / err) {if (err) throw err; console.log ('success'}) create a folder (fs.mkdir)

Definition: fs.mkdir (path [, mode], callback)

Parameter: mode defaults to to 0777.

Fs.mkdir ('. / tAccording) 0777 Magi function (err) {if (err) throw err; console.log ('success')) File Monitoring (fs.watch fs.watchFile)

Definition: fs.watch (filename [, options] [, listener])

Definition: fs.watchFile (filename [, options], listener)

Fs.watch ('test.js', function (event, filename) {}); fs.watchFile (' test.js', function (curr, prev) {}); flagsFlag describes r to open the file in read mode. Throw an exception if the file does not exist. R + opens the file in read-write mode. Throw an exception if the file does not exist. Rs reads files synchronously. Rs+ reads and writes files synchronously. W opens the file in write mode and creates it if the file does not exist. Wx is similar to'wicked, but if the file path exists, the file write fails. W + opens the file in read-write mode and creates it if the file does not exist. Wx+ is similar to'wicked written', but if the file path exists, the file fails to read and write. An opens the file in append mode and creates it if the file does not exist. Ax is similar to'a file, but if the file path exists, the file append fails. A + opens the file in read append mode and creates it if the file does not exist. Ax+ is similar to 'ajar', but if the file path exists, the file read append fails.

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