Node.js fs.accessSync()方法
原文:https://www.geeksforgeeks.org/node-js-fs-accesssync-method/
fs.accessSync()方法用于同步测试给定文件或目录的权限。要检查的权限可以使用文件访问常数指定为参数。还可以通过使用按位“或”运算符创建一个具有多个文件常量的掩码来检查多个文件权限。
语法:
fs.accessSync( path, mode )
参数:该方法接受两个参数，如上所述，如下所述:
- Path: It is a string, buffer or web address, which indicates the path of the file or directory whose permissions must be tested.
- Mode: indicates an integer value requiring test permission. The logical or operator can be used to separate multiple permissions. It can have values
fs.constants.F_OK,fs.constants.R_OK,fs.constants.W_OKandfs.constants.X_OK. This is an optional parameter. The default value isfs.constants.F_OK.
下面的例子说明了 Node.js 中的 fs.accessSync()方法:
示例 1: 此示例显示了文件读写权限的测试。
// Node.js program to demonstrate the
// fs.accessSync() method
// Import the filesystem module
const fs = require('fs');
// Allowing only read permission
console.log("Giving only read permission to user");
fs.chmodSync("example.txt", fs.constants.S_IRUSR);
// Test the read permission
console.log('\n> Checking Permission for reading the file');
try {
fs.accessSync('example.txt', fs.constants.R_OK);
console.log('File can be read');
} catch (err) {
console.error('No Read access');
}
// Test both the read and write permission
console.log('\n> Checking Permission for reading and writing to file');
try {
fs.accessSync('example.txt', fs.constants.R_OK | fs.constants.W_OK);
console.log('File can be read and written');
} catch (err) {
console.error('No Read and Write access');
}
输出:
Giving only read permission to user
> Checking Permission for reading the file
File can be read
> Checking Permission for reading and writing to file
No Read and Write access
示例 2: 此示例显示了文件存在时的测试。
// Node.js program to demonstrate the
// fs.accessSync() method
// Import the filesystem module
const fs = require('fs');
// Test the if the file exists
console.log('\n> Checking if the file exists');
try {
fs.accessSync('example.txt', fs.constants.F_OK);
console.log('File does exist');
} catch (err) {
console.error('File does not exist');
}
console.log('\nCreating the file');
fs.writeFileSync("example.txt", "Test File");
// Test the if the file exists again
console.log('\n> Checking if the file exists');
try {
fs.accessSync('example.txt', fs.constants.F_OK);
console.log('File does exist');
} catch (err) {
console.error('File does not exist');
}
输出:
> Checking if the file exists
File does not exist
Creating the file
> Checking if the file exists
File does exist
参考:https://nodejs . org/API/fs . html # fs _ fs _ accesssync _ path _ mode
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