Node.js fs.fstatSync() Method

Last Updated : 11 Oct, 2021
The fs.fstatSync() method is used to synchronously return information about the given file descriptor. The fs.Stat object returns several fields and methods to get more details about the file. Syntax: 
fstatSync( fd, options )
Parameters: This method accept two parameters as mentioned above and described below:
  • fd: It is an integer value which represents the file descriptor used by the method.
  • options: It is an object that can be used to specify optional parameters that will affect the output. It has one optional parameter:
    • bigint: It is a boolean value which specifies if the numeric values returned in the fs.Stats object are bigint. The default value is false.
Below examples illustrate the fs.fstatSync() method in Node.js: Example 1: This example uses fs.fstatSync() method to get the details of a file and directory. javascript 
// Node.js program to demonstrate the
// fs.fstatSync() method

// Import the filesystem module
const fs = require('fs');

const file_fd = fs.openSync('example_file.txt', 'r');

// Getting information for a file
let fileStat = fs.fstatSync(file_fd);

console.log("Stats object for: example_file.txt");
console.log(fileStat);

// Using methods of the Stats object
console.log("Path is file:", fileStat.isFile());
console.log("Path is directory:", fileStat.isDirectory());

const dir_fd = fs.openSync('example_directory', 'r');

// Getting information for a directory
let dirStat = fs.fstatSync(dir_fd);

console.log("Stats object for: example_directory");
console.log(dirStat);

// Using methods of the Stats object
console.log("Path is file:", dirStat.isFile());
console.log("Path is directory:", dirStat.isDirectory());
Output: 
Stats object for: example_file.txt
Stats {
  dev: 3229478529,
  mode: 33206,
  nlink: 1,
  uid: 0,
  gid: 0,
  rdev: 0,
  blksize: 4096,
  ino: 281474976780786,
  size: 0,
  blocks: 0,
  atimeMs: 1584961030299.117,
  mtimeMs: 1582209885466.6848,
  ctimeMs: 1582209885466.6848,
  birthtimeMs: 1584961030299.117,
  atime: 2020-03-23T10:57:10.299Z,
  mtime: 2020-02-20T14:44:45.467Z,
  ctime: 2020-02-20T14:44:45.467Z,
  birthtime: 2020-03-23T10:57:10.299Z
}
Path is file: true
Path is directory: false
Stats object for: example_directory
Stats {
  dev: 3229478529,
  mode: 16822,
  nlink: 1,
  uid: 0,
  gid: 0,
  rdev: 0,
  blksize: 4096,
  ino: 281474976780789,
  size: 0,
  blocks: 0,
  atimeMs: 1584961090214.9436,
  mtimeMs: 1581074249467.7114,
  ctimeMs: 1584961030324.12,
  birthtimeMs: 1584961030324.12,
  atime: 2020-03-23T10:58:10.215Z,
  mtime: 2020-02-07T11:17:29.468Z,
  ctime: 2020-03-23T10:57:10.324Z,
  birthtime: 2020-03-23T10:57:10.324Z
}
Path is file: false
Path is directory: true
Example 2: This example uses fs.fstatSync() method to get the details of a file with and without the bigint option. javascript 
// Node.js program to demonstrate the
// fs.fstatSync() method

// Import the filesystem module
const fs = require('fs');

const file_fd = fs.openSync('example_file.txt', 'r');

let fileStat = fs.fstatSync(file_fd);
console.log(fileStat);

// Using the bigint option to return
// the values in big integer format
let fileBigIntStat = fs.fstatSync(file_fd, { bigint: true });
console.log(fileBigIntStat);
Output: 
Stats {
  dev: 3229478529,
  mode: 33206,
  nlink: 1,
  uid: 0,
  gid: 0,
  rdev: 0,
  blksize: 4096,
  ino: 281474976780786,
  size: 0,
  blocks: 0,
  atimeMs: 1584961030299.117,
  mtimeMs: 1582209885466.6848,
  ctimeMs: 1582209885466.6848,
  birthtimeMs: 1584961030299.117,
  atime: 2020-03-23T10:57:10.299Z,
  mtime: 2020-02-20T14:44:45.467Z,
  ctime: 2020-02-20T14:44:45.467Z,
  birthtime: 2020-03-23T10:57:10.299Z
}
BigIntStats {
  dev: 3229478529n,
  mode: 33206n,
  nlink: 1n,
  uid: 0n,
  gid: 0n,
  rdev: 0n,
  blksize: 4096n,
  ino: 281474976780786n,
  size: 0n,
  blocks: 0n,
  atimeMs: 1584961030299n,
  mtimeMs: 1582209885466n,
  ctimeMs: 1582209885466n,
  birthtimeMs: 1584961030299n,
  atimeNs: 1584961030299117000n,
  mtimeNs: 1582209885466684900n,
  ctimeNs: 1582209885466684900n,
  birthtimeNs: 1584961030299117000n,
  atime: 2020-03-23T10:57:10.299Z,
  mtime: 2020-02-20T14:44:45.466Z,
  ctime: 2020-02-20T14:44:45.466Z,
  birthtime: 2020-03-23T10:57:10.299Z
}
Reference: https://nodejs.org/api/fs.html#fs_fs_fstatsync_fd_options
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