@ohos.file.fs (File Management)

The fs module provides APIs for file operations, including basic file management, directory management, file information statistics, and data read and write using a stream.

NOTE

The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import fs from '@ohos.file.fs';

Guidelines

Before using the APIs provided by this module to perform operations on a file or folder, obtain the application sandbox path of the file or folder as follows:

Stage Model

import UIAbility from '@ohos.app.ability.UIAbility';

export default class EntryAbility extends UIAbility {
   onWindowStageCreate(windowStage) {
       let context = this.context;
       let pathDir = context.filesDir;
   }
}

FA Model

import featureAbility from '@ohos.ability.featureAbility';

let context = featureAbility.getContext();
context.getFilesDir().then((data) => {
     let pathDir = data;
})

For details about how to obtain the FA model context, see Context.

fs.stat

stat(file: string|number): Promise<Stat>

Obtains detailed file information. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.stat(filePath).then((stat) => {
    console.info("get file info succeed, the size of file is " + stat.size);
}).catch((err) => {
    console.info("get file info failed with error message: " + err.message + ", error code: " + err.code);
});

fs.stat

stat(file: string|number, callback: AsyncCallback<Stat>): void

Obtains detailed file information. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

fs.stat(pathDir, (err, stat) => {
  if (err) {
    console.info("get file info failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("get file info succeed, the size of file is " + stat.size);
  }
});

fs.statSync

statSync(file: string|number): Stat

Obtains detailed file information synchronously.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let stat = fs.statSync(pathDir);
console.info("get file info succeed, the size of file is " + stat.size);

fs.access

access(path: string): Promise<boolean>

Checks whether a file exists. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.access(filePath).then((res) => {
  if (res) {
    console.info("file exists");
  }
}).catch((err) => {
  console.info("access failed with error message: " + err.message + ", error code: " + err.code);
});

fs.access

access(path: string, callback: AsyncCallback<boolean>): void

Checks whether a file exists. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.access(filePath, (err, res) => {
  if (err) {
    console.info("access failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    if (res) {
      console.info("file exists");
    }
  }
});

fs.accessSync

accessSync(path: string): boolean

Synchronously checks whether a file exists.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
try {
    let res = fs.accessSync(filePath);
    if (res) {
      console.info("file exists");
    }
} catch(err) {
    console.info("accessSync failed with error message: " + err.message + ", error code: " + err.code);
}

fs.close

close(file: File|number): Promise<void>

Closes a file. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
fs.close(file).then(() => {
    console.info("File closed");
    fs.closeSync(file);
}).catch((err) => {
    console.info("close file failed with error message: " + err.message + ", error code: " + err.code);
});

fs.close

close(file: File|number, callback: AsyncCallback<void>): void

Closes a file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
fs.close(file, (err) => {
  if (err) {
    console.info("close file failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("close file success");
  }
});

fs.closeSync

closeSync(file: File|number): void

Synchronously closes a file.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
fs.closeSync(file);

fs.copyFile

copyFile(src: string|number, dest: string|number, mode?: number): Promise<void>

Copies a file. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcPath = pathDir + "/srcDir/test.txt";
let dstPath = pathDir + "/dstDir/test.txt";
fs.copyFile(srcPath, dstPath).then(() => {
    console.info("copy file succeed");
}).catch((err) => {
    console.info("copy file failed with error message: " + err.message + ", error code: " + err.code);
});

fs.copyFile

copyFile(src: string|number, dest: string|number, mode?: number, callback: AsyncCallback<void>): void

Copies a file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcPath = pathDir + "/srcDir/test.txt";
let dstPath = pathDir + "/dstDir/test.txt";
fs.copyFile(srcPath, dstPath, (err) => {
  if (err) {
    console.info("copy file failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("copy file success");
  }
});

fs.copyFileSync

copyFileSync(src: string|number, dest: string|number, mode?: number): void

Synchronously copies a file.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcPath = pathDir + "/srcDir/test.txt";
let dstPath = pathDir + "/dstDir/test.txt";
fs.copyFileSync(srcPath, dstPath);

fs.mkdir

mkdir(path: string): Promise<void>

Creates a directory. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let dirPath = pathDir + "/testDir";
fs.mkdir(dirPath).then(() => {
    console.info("Directory created");
}).catch((err) => {
    console.info("mkdir failed with error message: " + err.message + ", error code: " + err.code);
});

fs.mkdir

mkdir(path: string, callback: AsyncCallback<void>): void

Creates a directory. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let dirPath = pathDir + "/testDir";
fs.mkdir(dirPath, (err) => {
  if (err) {
    console.info("mkdir failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("mkdir success");
  }
});

fs.mkdirSync

mkdirSync(path: string): void

Synchronously creates a directory.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let dirPath = pathDir + "/testDir";
fs.mkdirSync(dirPath);

fs.open

open(path: string, mode?: number): Promise<File>

Opens a file. This API uses a promise to return the result. File uniform resource identifiers (URIs) are supported.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.open(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE).then((file) => {
    console.info("file fd: " + file.fd);
}).catch((err) => {
    console.info("open file failed with error message: " + err.message + ", error code: " + err.code);
});

fs.open

open(path: string, mode?: number, callback: AsyncCallback<File>): void

Opens a file. This API uses an asynchronous callback to return the result. File URIs are supported.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.open(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE, (err, file) => {
  if (err) {
    console.info("mkdir failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("file fd: " + file.fd);
  }
});

fs.openSync

openSync(path: string, mode?: number): File

Synchronously opens a file. File URIs are supported.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
console.info("file fd: " + file.fd);
fs.closeSync(file);

fs.read

read(fd: number, buffer: ArrayBuffer, options?: { offset?: number; length?: number; }): Promise<number>

Reads data from a file. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE);
let buf = new ArrayBuffer(4096);
fs.read(file.fd, buf).then((readLen) => {
    console.info("Read file data successfully");
    console.info(String.fromCharCode.apply(null, new Uint8Array(buf.slice(0, readLen))));
    fs.closeSync(file);
}).catch((err) => {
    console.info("read file data failed with error message: " + err.message + ", error code: " + err.code);
});

fs.read

read(fd: number, buffer: ArrayBuffer, options?: { offset?: number; length?: number; }, callback: AsyncCallback<number>): void

Reads data from a file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE);
let buf = new ArrayBuffer(4096);
fs.read(file.fd, buf, (err, readLen) => {
  if (err) {
    console.info("mkdir failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("Read file data successfully");
    console.info(String.fromCharCode.apply(null, new Uint8Array(buf.slice(0, readLen))));
    fs.closeSync(file);
  }
});

fs.readSync

readSync(fd: number, buffer: ArrayBuffer, options?: { offset?: number; length?: number; }): number

Synchronously reads data from a file.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE);
let buf = new ArrayBuffer(4096);
let num = fs.readSync(file.fd, buf);
fs.closeSync(file);

fs.rmdir

rmdir(path: string): Promise<void>

Deletes a directory. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let dirPath = pathDir + "/testDir";
fs.rmdir(dirPath).then(() => {
    console.info("Directory deleted");
}).catch((err) => {
    console.info("rmdir failed with error message: " + err.message + ", error code: " + err.code);
});

fs.rmdir

rmdir(path: string, callback: AsyncCallback<void>): void

Deletes a directory. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let dirPath = pathDir + "/testDir";
fs.rmdir(dirPath, (err) => {
  if (err) {
    console.info("rmdir failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("Directory deleted");
  }
});

fs.rmdirSync

rmdirSync(path: string): void

Synchronously deletes a directory.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let dirPath = pathDir + "/testDir";
fs.rmdirSync(dirPath);

fs.unlink

unlink(path: string): Promise<void>

Deletes a file. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.unlink(filePath).then(() => {
    console.info("File deleted");
}).catch((err) => {
    console.info("remove file failed with error message: " + err.message + ", error code: " + err.codeor);
});

fs.unlink

unlink(path: string, callback: AsyncCallback<void>): void

Deletes a file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.unlink(filePath, (err) => {
  if (err) {
    console.info("remove file failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("File deleted");
  }
});

fs.unlinkSync

unlinkSync(path: string): void

Synchronously deletes a file.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.unlinkSync(filePath);

fs.write

write(fd: number, buffer: ArrayBuffer|string, options?: { offset?: number; length?: number; encoding?: string; }): Promise<number>

Writes data into a file. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
fs.write(file.fd, "hello, world").then((writeLen) => {
  console.info("write data to file succeed and size is:" + writeLen);
  fs.closeSync(file);
}).catch((err) => {
  console.info("write data to file failed with error message: " + err.message + ", error code: " + err.code);
});

fs.write

write(fd: number, buffer: ArrayBuffer|string, options?: { offset?: number; length?: number; encoding?: string; }, callback: AsyncCallback<number>): void

Writes data into a file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
fs.write(file.fd, "hello, world", (err, writeLen) => {
  if (err) {
    console.info("write failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("write data to file succeed and size is:" + writeLen);
    fs.closeSync(file);
  }
});

fs.writeSync

writeSync(fd: number, buffer: ArrayBuffer|string, options?: { offset?: number; length?: number; encoding?: string; }): number

Synchronously writes data into a file.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
let writeLen = fs.writeSync(file.fd, "hello, world");
console.info("write data to file succeed and size is:" + writeLen);
fs.closeSync(file);

fs.truncate

truncate(file: string|number, len?: number): Promise<void>

Truncates a file. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let len = 5;
fs.truncate(filePath, len).then(() => {
    console.info("File truncated");
}).catch((err) => {
    console.info("truncate file failed with error message: " + err.message + ", error code: " + err.code);
});

fs.truncate

truncate(file: string|number, len?: number, callback: AsyncCallback<void>): void

Truncates a file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let len = 5;
fs.truncate(filePath, len, (err) => {
  if (err) {
    console.info("truncate failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("truncate success");
  }
});

fs.truncateSync

truncateSync(file: string|number, len?: number): void

Synchronously truncates a file.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let len = 5;
fs.truncateSync(filePath, len);

fs.readText

readText(filePath: string, options?: { offset?: number; length?: number; encoding?: string; }): Promise<string>

Reads the text content of a file. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.readText(filePath).then((str) => {
    console.info("readText succeed:" + str);
}).catch((err) => {
    console.info("readText failed with error message: " + err.message + ", error code: " + err.code);
});

fs.readText

readText(filePath: string, options?: { offset?: number; length?: number; encoding?: string; }, callback: AsyncCallback<string>): void

Reads the text content of a file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.readText(filePath, { offset: 1, encoding: 'UTF-8' }, (err, str) => {
  if (err) {
    console.info("read text failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("readText succeed:" + str);
  }
});

fs.readTextSync

readTextSync(filePath: string, options?: { offset?: number; length?: number; encoding?: string; }): string

Synchronously reads the text of a file.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let str = fs.readTextSync(filePath, {offset: 1, length: 3});
console.info("readText succeed:" + str);

fs.lstat

lstat(path: string): Promise<Stat>

Obtains information about a symbolic link. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.lstat(filePath).then((stat) => {
    console.info("get link status succeed, the size of file is" + stat.size);
}).catch((err) => {
    console.info("get link status failed with error message: " + err.message + ", error code: " + err.code);
});

fs.lstat

lstat(path: string, callback: AsyncCallback<Stat>): void

Obtains information about a symbolic link. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.lstat(filePath, (err, stat) => {
    if (err) {
      console.info("lstat failed with error message: " + err.message + ", error code: " + err.code);
    } else {
      console.info("get link status succeed, the size of file is" + stat.size);
    }
});

fs.lstatSync

lstatSync(path: string): Stat

Obtains information about a symbolic link synchronously.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let stat = fs.lstatSync(filePath);

fs.rename

rename(oldPath: string, newPath: string): Promise<void>

Renames a file or folder. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcFile = pathDir + "/test.txt";
let dstFile = pathDir + "/new.txt";
fs.rename(srcFile, dstFile).then(() => {
    console.info("File renamed");
}).catch((err) => {
    console.info("rename failed with error message: " + err.message + ", error code: " + err.code);
});

fs.rename

rename(oldPath: string, newPath: string, callback: AsyncCallback<void>): void

Renames a file or folder. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcFile = pathDir + "/test.txt";
let dstFile = pathDir + "/new.txt";
fs.rename(srcFile, dstFile, (err) => {
  if (err) {
    console.info("rename failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("rename success");
  }
});

fs.renameSync

renameSync(oldPath: string, newPath: string): void

Renames a file or folder synchronously.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcFile = pathDir + "/test.txt";
let dstFile = pathDir + "/new.txt";
fs.renameSync(srcFile, dstFile);

fs.fsync

fsync(fd: number): Promise<void>

Flushes data of a file to disk. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
fs.fsync(file.fd).then(() => {
    console.info("Data flushed");
}).catch((err) => {
    console.info("sync data failed with error message: " + err.message + ", error code: " + err.code);
});

fs.fsync

fsync(fd: number, callback: AsyncCallback<void>): void

Flushes data of a file to disk. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
fs.fsync(file.fd, (err) => {
  if (err) {
    console.info("fsync failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("fsync success");
    fs.closeSync(file);
  }
});

fs.fsyncSync

fsyncSync(fd: number): void

Flushes data of a file to disk synchronously.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
fs.fsyncSync(file.fd);
fs.closeSync(file);

fs.fdatasync

fdatasync(fd: number): Promise<void>

Flushes data of a file to disk. This API uses a promise to return the result. fdatasync() is similar to fsync(), but does not flush modified metadata unless that metadata is needed.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
fs.fdatasync(file.fd).then((err) => {
  console.info("Data flushed");
  fs.closeSync(file);
}).catch((err) => {
  console.info("sync data failed with error message: " + err.message + ", error code: " + err.code);
});

fs.fdatasync

fdatasync(fd: number, callback: AsyncCallback<void>): void

Flushes data of a file to disk. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
fs.fdatasync (file.fd, (err) => {
  if (err) {
    console.info("fdatasync failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("fdatasync success");
    fs.closeSync(file);
  }
});

fs.fdatasyncSync

fdatasyncSync(fd: number): void

Synchronizes data in a file synchronously.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
let stat = fs.fdatasyncSync(file.fd);
fs.closeSync(file);

fs.symlink

symlink(target: string, srcPath: string): Promise<void>

Creates a symbolic link based on a file path. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcFile = pathDir + "/test.txt";
let dstFile = pathDir + "/test";
fs.symlink(srcFile, dstFile).then(() => {
    console.info("Symbolic link created");
}).catch((err) => {
    console.info("symlink failed with error message: " + err.message + ", error code: " + err.code);
});

fs.symlink

symlink(target: string, srcPath: string, callback: AsyncCallback<void>): void

Creates a symbolic link based on a file path. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcFile = pathDir + "/test.txt";
let dstFile = pathDir + "/test";
fs.symlink(srcFile, dstFile, (err) => {
  if (err) {
    console.info("symlink failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("symlink success");
  }
});

fs.symlinkSync

symlinkSync(target: string, srcPath: string): void

Synchronously creates a symbolic link based on a file path.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcFile = pathDir + "/test.txt";
let dstFile = pathDir + "/test";
fs.symlinkSync(srcFile, dstFile);

fs.listFile

listFile(path: string, options?: { recursion?: boolean; listNum?: number; filter?: Filter; }): Promise<string[]>

Lists all files in a directory. This API uses a promise to return the result.
This API supports recursive listing of all files (including files in subdirectories) and file filtering.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

options parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let options = {
  "recursion": false,
  "listNum": 0,
  "filter": {
    "suffix": [".png", ".jpg", ".jpeg"],
    "displayName": ["%abc", "efg%"],
    "fileSizeOver": 1024,
    "lastModifiedAfter": new Date().getTime(),
  }
};
fs.listFile(pathDir, options).then((filenames) => {
  console.info("listFile succeed");
  for (let i = 0; i < filenames.length; i++) {
    console.info("fileName: %s", filenames[i]);
  }
}).catch((err) => {
    console.info("list file failed with error message: " + err.message + ", error code: " + err.code);
});

fs.listFile

listFile(path: string, options?: { recursion?: boolean; listNum?: number; filter?: Filter; }, callback: AsyncCallback<string[]>): void

Lists all files in a directory. This API uses an asynchronous callback to return the result.
This API supports recursive listing of all files (including files in subdirectories) and file filtering.

Parameters

options parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let options = {
  "recursion": false,
  "listNum": 0,
  "filter": {
    "suffix": [".png", ".jpg", ".jpeg"],
    "displayName": ["%abc", "efg%"],
    "fileSizeOver": 1024,
    "lastModifiedAfter": new Date().getTime(),
  }
};
fs.listFile(pathDir, options, (err, filenames) => {
  if (err) {
    console.info("list file failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("listFile succeed");
    for (let i = 0; i < filenames.length; i++) {
      console.info("filename: %s", filenames[i]);
    }
  }
});

fs.listFileSync

listFileSync(path: string, options?: { recursion?: boolean; listNum?: number; filter?: Filter; }): string[]

Lists all files in a directory synchronously. This API supports recursive listing of all files (including files in subdirectories) and file filtering.

Parameters

options parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let options = {
  "recursion": false,
  "listNum": 0,
  "filter": {
    "suffix": [".png", ".jpg", ".jpeg"],
    "displayName": ["%abc", "efg%"],
    "fileSizeOver": 1024,
    "lastModifiedAfter": new Date().getTime(),
  }
};
let filenames = fs.listFileSync(pathDir, options);
console.info("listFile succeed");
for (let i = 0; i < filenames.length; i++) {
  console.info("filename: %s", filenames[i]);
}

fs.moveFile

moveFile(src: string, dest: string, mode?: number): Promise<void>

Moves a file. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcPath = pathDir + "/source.txt";
let destPath = pathDir + "/dest.txt";
fs.moveFile(srcPath, destPath, 0).then(() => {
    console.info("move file succeed");
}).catch((err) => {
    console.info("move file failed with error message: " + err.message + ", error code: " + err.code);
});

fs.moveFile

moveFile(src: string, dest: string, mode?: number, callback: AsyncCallback<void>): void

Moves a file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcPath = pathDir + "/source.txt";
let destPath = pathDir + "/dest.txt";
fs.moveFile(srcPath, destPath, 0, (err) => {
  if (err) {
    console.info("move file failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("move file succeed");
  }  
});

fs.moveFileSync

moveFile(src: string, dest: string, mode?: number): void

Moves a file synchronously.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let srcPath = pathDir + "/source.txt";
let destPath = pathDir + "/dest.txt";
fs.moveFileSync(srcPath, destPath, 0);
console.info("move file succeed");

fs.mkdtemp

mkdtemp(prefix: string): Promise<string>

Creates a temporary directory. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

fs.mkdtemp(pathDir + "/XXXXXX").then((pathDir) => {
    console.info("mkdtemp succeed:" + pathDir);
}).catch((err) => {
    console.info("mkdtemp failed with error message: " + err.message + ", error code: " + err.code);
});

fs.mkdtemp

mkdtemp(prefix: string, callback: AsyncCallback<string>): void

Creates a temporary directory. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

fs.mkdtemp(pathDir + "/XXXXXX", (err, res) => {
  if (err) {
    console.info("mkdtemp failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("mkdtemp success");
  }
});

fs.mkdtempSync

mkdtempSync(prefix: string): string

Synchronously creates a temporary directory.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let res = fs.mkdtempSync(pathDir + "/XXXXXX");

fs.createStream

createStream(path: string, mode: string): Promise<Stream>

Creates a stream based on the file path. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.createStream(filePath, "r+").then((stream) => {
    console.info("Stream created");
}).catch((err) => {
    console.info("createStream failed with error message: " + err.message + ", error code: " + err.code);
});

fs.createStream

createStream(path: string, mode: string, callback: AsyncCallback<Stream>): void

Creates a stream based on the file path. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
fs.createStream(filePath, "r+", (err, stream) => {
  if (err) {
    console.info("create stream failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("create stream success");
  }
});

fs.createStreamSync

createStreamSync(path: string, mode: string): Stream

Synchronously creates a stream based on the file path.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss = fs.createStreamSync(filePath, "r+");

fs.fdopenStream

fdopenStream(fd: number, mode: string): Promise<Stream>

Opens a stream based on the file descriptor. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath);
fs.fdopenStream(file.fd, "r+").then((stream) => {
    console.info("Stream opened");
    fs.closeSync(file);
}).catch((err) => {
    console.info("openStream failed with error message: " + err.message + ", error code: " + err.code);
});

fs.fdopenStream

fdopenStream(fd: number, mode: string, callback: AsyncCallback<Stream>): void

Opens a stream based on the file descriptor. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath, fs.OpenMode.READ_ONLY);
fs.fdopenStream(file.fd, "r+", (err, stream) => {
  if (err) {
    console.info("fdopen stream failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("fdopen stream success");
    fs.closeSync(file);
  }
});

fs.fdopenStreamSync

fdopenStreamSync(fd: number, mode: string): Stream

Synchronously opens a stream based on the file descriptor.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let file = fs.openSync(filePath, fs.OpenMode.READ_ONLY | fs.OpenMode.CREATE);
let ss = fs.fdopenStreamSync(file.fd, "r+");
fs.closeSync(file);

Stat

Represents detailed file information. Before calling any API of the Stat() class, use stat() to create a Stat instance synchronously or asynchronously.

System capability: SystemCapability.FileManagement.File.FileIO

Attributes

isBlockDevice

isBlockDevice(): boolean

Checks whether this file is a block special file. A block special file supports access by block only, and it is cached when accessed.

System capability: SystemCapability.FileManagement.File.FileIO

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let isBLockDevice = fs.statSync(filePath).isBlockDevice();

isCharacterDevice

isCharacterDevice(): boolean

Checks whether this file is a character special file. A character special file supports random access, and it is not cached when accessed.

System capability: SystemCapability.FileManagement.File.FileIO

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let isCharacterDevice = fs.statSync(filePath).isCharacterDevice();

isDirectory

isDirectory(): boolean

Checks whether this file is a directory.

System capability: SystemCapability.FileManagement.File.FileIO

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let dirPath = pathDir + "/test";
let isDirectory = fs.statSync(dirPath).isDirectory(); 

isFIFO

isFIFO(): boolean

Checks whether this file is a named pipe (or FIFO). Named pipes are used for inter-process communication.

System capability: SystemCapability.FileManagement.File.FileIO

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let isFIFO = fs.statSync(filePath).isFIFO(); 

isFile

isFile(): boolean

Checks whether this file is a regular file.

System capability: SystemCapability.FileManagement.File.FileIO

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let isFile = fs.statSync(filePath).isFile();

isSocket

isSocket(): boolean

Checks whether this file is a socket.

System capability: SystemCapability.FileManagement.File.FileIO

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let isSocket = fs.statSync(filePath).isSocket(); 

isSymbolicLink

isSymbolicLink(): boolean

Checks whether this file is a symbolic link.

System capability: SystemCapability.FileManagement.File.FileIO

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test";
let isSymbolicLink = fs.statSync(filePath).isSymbolicLink(); 

Stream

Provides a stream for file operations. Before calling any API of the Stream class, use createStream() to create a Stream instance synchronously or asynchronously.

close

close(): Promise<void>

Closes the stream. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss= fs.createStreamSync(filePath, "r+");
ss.close().then(() => {
    console.info("File stream closed");
}).catch((err) => {
    console.info("close fileStream  failed with error message: " + err.message + ", error code: " + err.code);
});

close

close(callback: AsyncCallback<void>): void

Closes the stream. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss= fs.createStreamSync(filePath, "r+");
ss.close((err) => {
  if (err) {
    console.info("close stream failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("close stream success"):
  }
});

closeSync

closeSync(): void

Synchronously closes the stream.

System capability: SystemCapability.FileManagement.File.FileIO

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss= fs.createStreamSync(filePath, "r+");
ss.closeSync();

flush

flush(): Promise<void>

Flushes the stream. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss= fs.createStreamSync(filePath, "r+");
ss.flush().then(() => {
    console.info("Stream flushed");
}).catch((err) => {
    console.info("flush failed with error message: " + err.message + ", error code: " + err.code);
});

flush

flush(callback: AsyncCallback<void>): void

Flushes the stream. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss= fs.createStreamSync(filePath, "r+");
ss.flush((err) => {
  if (err) {
    console.info("flush stream failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("flush success");
  }
});

flushSync

flushSync(): void

Synchronously flushes the stream.

System capability: SystemCapability.FileManagement.File.FileIO

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss= fs.createStreamSync(filePath, "r+");
ss.flushSync();

write

write(buffer: ArrayBuffer|string, options?: { offset?: number; length?: number; encoding?: string; }): Promise<number>

Writes data into the stream. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss= fs.createStreamSync(filePath, "r+");
ss.write("hello, world",{ offset: 5, length: 5, encoding: 'utf-8' }).then((number) => {
    console.info("write succeed and size is:" + number);
}).catch((err) => {
    console.info("write failed with error message: " + err.message + ", error code: " + err.code);
});

write

write(buffer: ArrayBuffer|string, options?: { offset?: number; length?: number; encoding?: string; }, callback: AsyncCallback<number>): void

Writes data into the stream. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss= fs.createStreamSync(filePath, "r+");
ss.write("hello, world", { offset: 5, length: 5, encoding :'utf-8'}, (err, bytesWritten) => {
  if (err) {
    console.info("write stream failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    if (bytesWritten) {
      console.info("write succeed and size is:" + bytesWritten);
    }
  }
});

writeSync

writeSync(buffer: ArrayBuffer|string, options?: { offset?: number; length?: number; encoding?: string; }): number

Synchronously writes data into the stream.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss= fs.createStreamSync(filePath,"r+");
let num = ss.writeSync("hello, world", {offset: 5, length: 5, encoding :'utf-8'});

read

read(buffer: ArrayBuffer, options?: { offset?: number; length?: number; }): Promise<number>

Reads data from the stream. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss = fs.createStreamSync(filePath, "r+");
let buf = new ArrayBuffer(4096);
ss.read(buf, {offset: 5, length: 5}).then((readLen) => {
  console.info("Read data successfully");
  console.log(String.fromCharCode.apply(null, new Uint8Array(buf.slice(0, readLen))));
}).catch((err) => {
    console.info("read data failed with error message: " + err.message + ", error code: " + err.code);
});

read

read(buffer: ArrayBuffer, options?: { position?: number; offset?: number; length?: number; }, callback: AsyncCallback<number>): void

Reads data from the stream. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss = fs.createStreamSync(filePath, "r+");
let buf = new ArrayBuffer(4096)
ss.read(buf, {offset: 5, length: 5}, (err, readLen) => {
  if (err) {
    console.info("read stream failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.info("Read data successfully");
    console.log(String.fromCharCode.apply(null, new Uint8Array(buf.slice(0, readLen))));
  }
});

readSync

readSync(buffer: ArrayBuffer, options?: { offset?: number; length?: number; }): number

Synchronously reads data from the stream.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let filePath = pathDir + "/test.txt";
let ss = fs.createStreamSync(filePath, "r+");
let num = ss.readSync(new ArrayBuffer(4096), {offset: 5, length: 5});

File

Represents a File object opened by open().

System capability: SystemCapability.FileManagement.File.FileIO

Attributes

lock

lock(exclusive?: boolean): Promise<void>

Applies an exclusive lock or a shared lock on this file in blocking mode. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Return value

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let file = fs.openSync(path, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
file.lock(true).then(() => {
  console.log("lock file successful");
}).catch((err) => {
    console.info("lock file failed with error message: " + err.message + ", error code: " + err.code);
});

lock

lock(exclusive?: boolean, callback: AsyncCallback<void>): void

Applies an exclusive lock or a shared lock on this file in blocking mode. This API uses a promise to return the result.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let file = fs.openSync(path, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
file.lock(true, (err) => {
  if (err) {
    console.info("lock file failed with error message: " + err.message + ", error code: " + err.code);
  } else {
    console.log("lock file successful");
  }
});

tryLock

tryLock(exclusive?: boolean): void

Applies an exclusive lock or a shared lock on this file in non-blocking mode.

System capability: SystemCapability.FileManagement.File.FileIO

Parameters

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let file = fs.openSync(path, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
file.tryLock(true);
console.log("lock file successful");

unlock

unlock(): void

Unlocks this file synchronously.

System capability: SystemCapability.FileManagement.File.FileIO

Error codes

For details about error codes, see "Basic File I/O Error Codes" in File Management Error Codes.

Example

let file = fs.openSync(path, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
file.tryLock(true);
file.unlock();
console.log("unlock file successful");

OpenMode

Defines the constants of the mode parameter used in open(). It specifies the mode for opening a file.

System capability: SystemCapability.FileManagement.File.FileIO

Filter

System capability: SystemCapability.FileManagement.File.FileIO

Defines the file filtering configuration, which can be used by listFile().