深入了解nodejs spawn执行的流程深入分析child_process .spawn:生成子进程的能力，父子进程传

nodejs 官网介绍

The node:child_process module provides the ability to spawn subprocesses in a manner that is similar, but not identical, to popen(3). This capability is primarily provided by the child_process.spawn() function:

import { spawn } from 'node:child_process';
const ls = spawn('ls', ['-lh', '/usr']);

ls.stdout.on('data', (data) => {
  console.log(`stdout: ${data}`);
});

ls.stderr.on('data', (data) => {
  console.error(`stderr: ${data}`);
});

ls.on('close', (code) => {
  console.log(`child process exited with code ${code}`);
});

node:child_process 模块提供了以与 popen(3) 类似但不相同的方式生成子进程的能力。此功能主要由 child_process.spawn() 提供

应用场景

## child/src/index.ts =====  tsc ==> child/dist/index.js
import path from "node:path";

console.log("cwd:",process.cwd())
console.log("PARENT_VAR:",process.env.PARENT_VAR)
console.log("__filename:",path.dirname(__filename))

执行编译后的文件

node dist/index.js

执行结果：

cwd: ${workspace}/child
PARENT_VAR: undefined
__filename: ${workspace}/child/dist

## parent/src/index.ts =====  tsc ==> parent/dist/index.js
import { spawn } from "node:child_process";

let child = spawn(process.execPath, ["../child/dist/index.js"],{ stdio: "inherit" ,detached : true})
child.on("exit",()=>{
    console.log("child exit")
})
// stdout
child.stdout?.on("data", (data) => {
    console.log(`stdout: ${data}`);
});
// stderr
child.stderr?.on("data", (data) => {
    console.error(`stderr: ${data}`);
});
child.unref()

执行编译后的文件:

node dist/index.js

执行结果：

cwd: ${workspace}/parent
PARENT_VAR: undefined
__filename: ${workspace}/child/dist

更新parent/src/index.ts

import { spawn } from "node:child_process";
// 设置环境变量
process.env.PARENT_VAR="pppp"
let child = spawn(process.execPath, ["../child/dist/index.js"],{ stdio: "inherit" ,detached : true})
child.on("exit",()=>{
    console.log("child exit")
})
// stdout
child.stdout?.on("data", (data) => {
    console.log(`stdout: ${data}`);
});
// stderr
child.stderr?.on("data", (data) => {
    console.error(`stderr: ${data}`);
});
child.unref()

执行编译后的文件:

node dist/index.js

执行结果：

cwd: ${workspace}/parent
PARENT_VAR: pppp
__filename: ${workspace}/child/dist

在启动子进程的时候会把当前进程的环境变量传递过去：

`child_process.spawn(command[, args][, options])`

command The command to run.
args <string[]> List of string arguments.
options
- cwd | Current working directory of the child process.
- env Environment key-value pairs. Default: process.env.
- argv0 Explicitly set the value of argv[0] sent to the child process. This will be set to command if not specified.
- stdio | Child's stdio configuration (see options.stdio).
- detached Prepare child process to run independently of its parent process. Specific behavior depends on the platform (see options.detached).
- uid Sets the user identity of the process (see setuid(2)).
- gid Sets the group identity of the process (see setgid(2)).
- serialization Specify the kind of serialization used for sending messages between processes. Possible values are 'json' and 'advanced'. See Advanced serialization for more details. Default: 'json'.
- shell | If true, runs command inside of a shell. Uses '/bin/sh' on Unix, and process.env.ComSpec on Windows. A different shell can be specified as a string. See Shell requirements and Default Windows shell. Default: false (no shell).
- windowsVerbatimArguments No quoting or escaping of arguments is done on Windows. Ignored on Unix. This is set to true automatically when shell is specified and is CMD. Default: false.
- windowsHide Hide the subprocess console window that would normally be created on Windows systems. Default: false.
- signal allows aborting the child process using an AbortSignal.
- timeout In milliseconds the maximum amount of time the process is allowed to run. Default: undefined.
- killSignal | The signal value to be used when the spawned process will be killed by timeout or abort signal. Default: 'SIGTERM'.
- Returns: