Detailed explanation of using Node.js to write cross-platform spawn statements

The most powerful thing about Node.js is "cross-platform". With a little care when coding, your code will work across Windows, Linux, and OSX platforms. The following article mainly introduces how to use Node.js to write cross-platform spawn statements. Friends in need can refer to it.

Preface

Node.js is cross-platform, which means it can run on Windows, OSX and Linux platforms. Many Node.js developers develop on OSX and then deploy the code to Linux servers. Since both OSX and Linux are based on Unix, they have a lot in common. Windows is also an officially supported platform for Node.js. As long as you write code in the correct way, you can run it on various platforms without any pressure.

There is a spawn function under the child_process module of Node.js, which can be used to call commands on the system. For example, on Linux, macOS and other systems, we can execute

const spawn = require('child_process').spawn;

spawn('npm', {
 stdio: 'inherit'
});

to call npm command.

However, the same statement will report an error when executed on Windows.

Error: spawn npm ENOENT
 at exports._errnoException (util.js:855:11)
 at Process.ChildProcess._handle.onexit (internal/child_process.js:178:32)
 at onErrorNT (internal/child_process.js:344:16)
 at nextTickCallbackWith2Args (node.js:455:9)
 at process._tickCallback (node.js:369:17)
 at Function.Module.runMain (module.js:432:11)
 at startup (node.js:141:18)
 at node.js:980:3

Because on Windows, when we execute npm, we actually execute the npm.cmd batch, and on Windows, .cmd, . bat batch processing cannot be run independently of the cmd.exe interpreter.

Therefore, we need to explicitly call cmd

spawn('cmd', ['/c', 'npm'], {
 stdio: 'inherit'
});

or use when calling the spawn function, set the shell option to true to implicitly Call cmd (this option was added from Node.js v6 version)

spawn('npm', {
 stdio: 'inherit',
 shell: true
});

In addition, although there is no need to set the shell option on Linux, macOS and other systems, the command It can also be executed normally; setting shell to true will not hinder the execution of the command, but will generate an additional unnecessary shell process, affecting performance.

Therefore, if you want to write a cross-platform spawn command without adding additional overhead, you can write it like this

const process = require('process');
const { spawn } = require('child_process');

spawn('npm', {
 stdio: 'inherit',
 // 仅在当前运行环境为 Windows 时，才使用 shell
 shell: process.platform === 'win32'
});

Third-party module cross-spawn

Regarding the cross-platform writing method of the spawn function, in addition to handling it when writing the code yourself, there are also third-party modules that encapsulate the relevant details, such as cross-spawn.

Using this module, when calling the spawn function, it can automatically decide whether to generate a shell to execute the given command based on the current running platform.

Moreover, it can also

• support Node.js versions lower than v6 (using the shell option requires at least Node.js v6);

• Cross-platform support for shebang;

• It is more convenient to escape characters in commands and parameters.
  

Installation

npm install cross-spawn

Usage

const spawn = require('cross-spawn');

spawn('npm', {
 stdio: 'inherit'
});

For more detailed explanations of using Node.js to write cross-platform spawn statements, please pay attention to the PHP Chinese website!