subprocess.stdio

• <Array>

到子进程的稀疏管道数组，对应于传给 child_process.spawn() 的 stdio 选项中的位置，这些位置已设置为值 'pipe'。 subprocess.stdio[0]、subprocess.stdio[1] 和 subprocess.stdio[2] 也可分别用作 subprocess.stdin、subprocess.stdout 和 subprocess.stderr。

在下面的例子中，只有子进程的文件描述符 1 (标准输出) 被配置为管道，所以只有进程的 subprocess.stdio[1] 是流，数组中的所有其他值都是 null。

const assert = require('node:assert');
const fs = require('node:fs');
const child_process = require('node:child_process');

const subprocess = child_process.spawn('ls', {
  stdio: [
    0, // 为子进程使用父进程的标准输入。
    'pipe', // 管道子进程的标准输出到父进程。
    fs.openSync('err.out', 'w'), // 将子进程的标准错误定向到文件。
  ]
});

assert.strictEqual(subprocess.stdio[0], null);
assert.strictEqual(subprocess.stdio[0], subprocess.stdin);

assert(subprocess.stdout);
assert.strictEqual(subprocess.stdio[1], subprocess.stdout);

assert.strictEqual(subprocess.stdio[2], null);
assert.strictEqual(subprocess.stdio[2], subprocess.stderr);

如果无法成功衍生子进程，则 subprocess.stdio 属性可能是 undefined。

• <Array>

A sparse array of pipes to the child process, corresponding with positions in the stdio option passed to child_process.spawn() that have been set to the value 'pipe'. subprocess.stdio[0], subprocess.stdio[1], and subprocess.stdio[2] are also available as subprocess.stdin, subprocess.stdout, and subprocess.stderr, respectively.

In the following example, only the child's fd 1 (stdout) is configured as a pipe, so only the parent's subprocess.stdio[1] is a stream, all other values in the array are null.

const assert = require('node:assert');
const fs = require('node:fs');
const child_process = require('node:child_process');

const subprocess = child_process.spawn('ls', {
  stdio: [
    0, // Use parent's stdin for child.
    'pipe', // Pipe child's stdout to parent.
    fs.openSync('err.out', 'w'), // Direct child's stderr to a file.
  ]
});

assert.strictEqual(subprocess.stdio[0], null);
assert.strictEqual(subprocess.stdio[0], subprocess.stdin);

assert(subprocess.stdout);
assert.strictEqual(subprocess.stdio[1], subprocess.stdout);

assert.strictEqual(subprocess.stdio[2], null);
assert.strictEqual(subprocess.stdio[2], subprocess.stderr);

The subprocess.stdio property can be undefined if the child process could not be successfully spawned.