Node.js fs.filehandle.chown() 方法
fs.filehandle.chown()方法是文件系统模块中fs.filehandle类的内置应用程序编程接口,用于更改特定文件的所有权。
句法:
const filehandle.chown(uid, gid)
参数:此方法接受上面提到的两个参数,如下所述:
- uid: : 代表用户id。
- gid:表示组标识符。
返回值:此方法返回一个未包含任何值的待处理承诺。
下面的程序说明了fs.filehandle.chown()方法的使用。
示例 1:文件名:index.js
javascript
// Node.js program to demonstrate the
// filehandle.chown() method
const fs = require('fs');
const fsPromises = fs.promises;
console.log("content of file before operation :- "
+ (fs.readFileSync('example.txt')));
// Initiating asyncrionise function
async function funct() {
// Initializing filehandle
let filehandle = null;
try {
// Creating and initiating filehandle
filehandle = await
fsPromises.open('example.txt', 'r+');
// Modifying the file ownership
// by using chown() method
const prom = filehandle.chown(1, 1);
} finally {
if (filehandle) {
// Close the file if it is opened.
console.log("ownership is changed"
+ " successfully");
console.log("content of file after"
+ " operation :- " +
(fs.readFileSync('example.txt')));
await filehandle.close();
}
}
}
funct().catch(console.error);
javascript
// Node.js program to demonstrate the
// filehandle.chown() method
const fs = require('fs');
const fsPromises = fs.promises;
// Data for the new file
let data = "This is a file containing "
+ "a collection of books.";
// Name of the file to be created
let file = "books.txt";
// Creating the new file 'books.txt'
fs.writeFile(file, data, (err) => {
// Catching error
if (err) {
console.log(err);
}
});
// Using fs.exists() method
fs.exists(file, (exists) => {
if (exists) {
console.log("content of file"
+ " before operation :- " +
(fs.readFileSync(file)));
}
});
// Initiating asyncrionise function
async function funct() {
// Initializing filehandle
let filehandle = null;
try {
// Creating and initiating
// filehandle
filehandle = await
fsPromises.open(file, 'r+');
// Modifying the file ownership
// by using chown() method
const prom = filehandle.chown(1, 1);
} finally {
if (filehandle) {
// Close the file if it is opened.
console.log("ownership is changed");
console.log("content of file "
+ "after operation :- " +
(fs.readFileSync(file)));
await filehandle.close();
}
}
}
funct().catch(console.error);
运行程序前的目录结构:
运行程序后的目录结构:
使用以下命令运行index.js文件:
node index.js
输出:
content of file before operation :- Content of example.txt file
ownership is changed successfully
content of file after operation :- Content of example.txt file
示例 2:文件名:index.js
javascript
// Node.js program to demonstrate the
// filehandle.chown() method
const fs = require('fs');
const fsPromises = fs.promises;
// Data for the new file
let data = "This is a file containing "
+ "a collection of books.";
// Name of the file to be created
let file = "books.txt";
// Creating the new file 'books.txt'
fs.writeFile(file, data, (err) => {
// Catching error
if (err) {
console.log(err);
}
});
// Using fs.exists() method
fs.exists(file, (exists) => {
if (exists) {
console.log("content of file"
+ " before operation :- " +
(fs.readFileSync(file)));
}
});
// Initiating asyncrionise function
async function funct() {
// Initializing filehandle
let filehandle = null;
try {
// Creating and initiating
// filehandle
filehandle = await
fsPromises.open(file, 'r+');
// Modifying the file ownership
// by using chown() method
const prom = filehandle.chown(1, 1);
} finally {
if (filehandle) {
// Close the file if it is opened.
console.log("ownership is changed");
console.log("content of file "
+ "after operation :- " +
(fs.readFileSync(file)));
await filehandle.close();
}
}
}
funct().catch(console.error);
运行程序前的目录结构:
运行程序后的目录结构:
使用以下命令运行index.js文件:
node index.js
输出:
content of file before operation :- This is a file containing a collection of books.
ownership is changed
content of file after operation :- This is a file containing a collection of books.
参考:
https://nodejs.org/dist/latest-v12.x/docs/api/fs.html#fs_filehandle_chown_uid_gid