File System (FS module)

One, open and close files//behave differently in different operating systems

• var fd=fs.open (Path,flags,[mode],callback)//Returns an integer representing the open file object
• Fs.close (Fd,callback)

Attached: Flags parameter table, indicating the mode of open file

• ' R ' -Open file for reading. An exception occurs if the file is does not exist.

• ‘r+‘-Open file for reading and writing. An exception occurs if the file is does not exist.

• ‘rs+‘-Open file for reading and writing in synchronous mode. Instructs the operating system to bypass the local file system cache.

  This is a primarily useful for opening files on NFS mounts as it allows you to skip the potentially stale local cache. It has a very real impact on I/O performance so don ' t use this flag unless you need it.

  Note that this doesn ' t turn to fs.open() a synchronous blocking call. If that's what's your want then should is usingfs.openSync()

• ‘w‘-Open file for writing. The file is created (if it does not exist) or truncated (if it exists).

• ‘wx‘-like but ‘w‘ fails if path exists.

• ‘w+‘-Open file for reading and writing. The file is created (if it does not exist) or truncated (if it exists).

• ‘wx+‘-like but ‘w+‘ fails if path exists.

• ‘a‘-Open file for appending. The file is created if it does not exist.

• ‘ax‘-like but ‘a‘ fails if path exists.

• ‘a+‘-Open file for reading and appending. The file is created if it does not exist.

• ‘ax+‘-like but ‘a+‘ fails if path exists.

Second, write the file

1. Simple File Writing

Fs.writefile (Filename,data,[opations],callback)

• Finename: Specify File
• Data: Specifies the string or buffer object that will be written to the file
• Opations: Is an object that can contain the encoding, mode, and flag properties that define the string encoding and the patterns and flags used when opening the file
• Callback: The function that is called when the file write is completed

2. synchronous file Writing

var fd=fs.opnesync (Path,flags[,mode])

Fs.writesync (Fd,buffer,offset,length[,position])

Fs.writesync (fd,data[,position][,encoding])

Fs.closesync (FD)

• Path: Specify file
• Flags: Specifies the mode in which the file is opened
• Mode: Sets the access pattern for the file
• FD: Integer, representing the file object, typically the return value of the Fs.open () function
• Data: Write to
• Buffer: Buffered data
• offset/length : Determines where to start writing to buffer.

3. Writing Files asynchronously

• Fs.open (path, flags[, mode], callback)//asynchronous write to file with callback (ERR,FD) function
• Fs.write (fd, buffer, offset, length[, position], callback)
• Fs.write (FD, data[, position[, encoding]], callback)
• Fs.close (FD)

4. Stream file Write

• var filewritestream=fs.createwritestream (Path[,options])
• Filewritestream.write (data)
• Filewritestream.on ("Close", Handler)//end method is called after execution
• Filewritestream.end ()

Third, read the file (IBID.)

1. Simple file reading

• Fs.readfile (file[, Options], callback)

2. synchronous file Reading

• Fs.readsync (fd, buffer, offset, length, position)

3. Asynchronous file read

• Fs.read (fd, buffer, offset, length, position, callback)

4. streaming file read

• Fs.createreadstream (path[, Options])
• Data event and Close event

Iv. Other File system tasks

1, Fs.stat (path, callback)//Get file information

• Stats.isfile ()//If the entry is a file, returns True
• stats.isDirectory()　　//如果条目是一个目录,返回true
• stats.isBlockDevice()　　//
• stats.isCharacterDevice()　　//
• stats.isSymbolicLink()(Only valid with Fs.lstat ())//
• stats.isFIFO()　　//
• stats.isSocket()　　如果条目是一个套接字,返回true

2. List files (all subdirectories of Path path are listed, stored as arrays)

• Fs.readdir (path[, Options], callback)

3. Delete Files

• Fs.unlink (Path,callback)

4. truncate files

• Fs.truncate (Path, Len, callback)//intercept Len length from the file and discard it later

5. Create and delete directories

• Fs.mkdir (path[, mode], callback)//established
• Fs.rmdir (path, callback)//delete

6. renaming files and directories

• Fs.rename (OldPath, NewPath, callback)

7. monitor file changes into

• Fs.watchfile (filename[, Options], listener)//options contains peristent (whether persistent) and interval (interval check) properties

File System (FS module)