我正在将一个CLI库从Ruby移植到Node.js.在我的代码中,我在必要时执行几个第三方二进制文件.我不确定在Node中如何最好地完成此任务.
这是Ruby中的一个示例,我将PrinceXML称为将文件转换为PDF:
cmd = system("prince -v builds/pdf/book.html -o builds/pdf/book.pdf")
Node中的等效代码是什么?
v12.9.1
,LTS v10.16.3
和v8.16.1
--- 2018年12月异步和正确的方法(Unix):
'use strict'; const { spawn } = require( 'child_process' ); const ls = spawn( 'ls', [ '-lh', '/usr' ] ); ls.stdout.on( 'data', data => { console.log( `stdout: ${data}` ); } ); ls.stderr.on( 'data', data => { console.log( `stderr: ${data}` ); } ); ls.on( 'close', code => { console.log( `child process exited with code ${code}` ); } );
异步方法(Windows):
'use strict'; const { spawn } = require( 'child_process' ); const dir = spawn( 'dir', [ '.' ] ); dir.stdout.on( 'data', data => console.log( `stdout: ${data}` ) ); dir.stderr.on( 'data', data => console.log( `stderr: ${data}` ) ); dir.on( 'close', code => console.log( `child process exited with code ${code}` ) );
同步:
'use strict'; const { spawnSync } = require( 'child_process' ); const ls = spawnSync( 'ls', [ '-lh', '/usr' ] ); console.log( `stderr: ${ls.stderr.toString()}` ); console.log( `stdout: ${ls.stdout.toString()}` );
来自Node.js v11.5.0文档
这同样适用于Node.js的v10.14.2文档和Node.js的v8.14.1文档
对于更新版本的Node.js(v8.1.4),事件和调用与旧版本类似或相同,但鼓励使用标准的新语言功能.例子:
对于缓冲的非流格式化输出(您可以一次性获取),请使用child_process.exec
:
const { exec } = require('child_process'); exec('cat *.js bad_file | wc -l', (err, stdout, stderr) => { if (err) { // node couldn't execute the command return; } // the *entire* stdout and stderr (buffered) console.log(`stdout: ${stdout}`); console.log(`stderr: ${stderr}`); });
您也可以将它与Promises一起使用:
const util = require('util'); const exec = util.promisify(require('child_process').exec); async function ls() { const { stdout, stderr } = await exec('ls'); console.log('stdout:', stdout); console.log('stderr:', stderr); } ls();
如果您希望以块的形式逐渐接收数据(以流形式输出),请使用child_process.spawn
:
const { spawn } = require('child_process'); const child = spawn('ls', ['-lh', '/usr']); // use child.stdout.setEncoding('utf8'); if you want text chunks child.stdout.on('data', (chunk) => { // data from standard output is here as buffers }); // since these are streams, you can pipe them elsewhere child.stderr.pipe(dest); child.on('close', (code) => { console.log(`child process exited with code ${code}`); });
这两个功能都具有同步功能.一个例子child_process.execSync
:
const { execSync } = require('child_process'); // stderr is sent to stderr of parent process // you can set options.stdio if you want it to go elsewhere let stdout = execSync('ls');
以及child_process.spawnSync
:
const { spawnSync} = require('child_process'); const child = spawnSync('ls', ['-lh', '/usr']); console.log('error', child.error); console.log('stdout ', child.stdout); console.log('stderr ', child.stderr);
注意:以下代码仍然有效,但主要针对ES5及之前的用户.
使用Node.js生成子进程的模块在文档(v5.0.0)中有详细记载.要执行命令并将其完整输出作为缓冲区获取,请使用child_process.exec
:
var exec = require('child_process').exec; var cmd = 'prince -v builds/pdf/book.html -o builds/pdf/book.pdf'; exec(cmd, function(error, stdout, stderr) { // command output is in stdout });
如果需要对流使用句柄处理I/O,例如当您需要大量输出时,请使用child_process.spawn
:
var spawn = require('child_process').spawn; var child = spawn('prince', [ '-v', 'builds/pdf/book.html', '-o', 'builds/pdf/book.pdf' ]); child.stdout.on('data', function(chunk) { // output will be here in chunks }); // or if you want to send output elsewhere child.stdout.pipe(dest);
如果您正在执行文件而不是命令,您可能希望使用child_process.execFile
哪些参数几乎相同spawn
,但具有第四个回调参数,例如exec
检索输出缓冲区.这可能看起来像这样:
var execFile = require('child_process').execFile; execFile(file, args, options, function(error, stdout, stderr) { // command output is in stdout });
从v0.11.12开始,Node现在支持同步spawn
和exec
.上述所有方法都是异步的,并且具有同步对应物.可在此处找到有关它们的文档.虽然它们对脚本很有用,但请注意,与用于异步生成子进程的方法不同,同步方法不返回实例ChildProcess
.
const exec = require("child_process").exec exec("ls", (error, stdout, stderr) => { //do whatever here })
您正在寻找child_process.exec
这是一个例子:
const exec = require('child_process').exec; const child = exec('cat *.js bad_file | wc -l', (error, stdout, stderr) => { console.log(`stdout: ${stdout}`); console.log(`stderr: ${stderr}`); if (error !== null) { console.log(`exec error: ${error}`); } });
如果你想要一些与最佳答案非常相似但又同步的东西,那么这将是有效的.
var execSync = require('child_process').execSync; var cmd = "echo 'hello world'"; var options = { encoding: 'utf8' }; console.log(execSync(cmd, options));
从版本4开始,最接近的方法是child_process.execSync
:
const {execSync} = require('child_process'); let output = execSync('prince -v builds/pdf/book.html -o builds/pdf/book.pdf');
请注意,此方法会阻止事件循环.
如果你不介意依赖并想要使用promises,那么child-process-promise
:
安装
npm install child-process-promise --save
exec用法
var exec = require('child-process-promise').exec; exec('echo hello') .then(function (result) { var stdout = result.stdout; var stderr = result.stderr; console.log('stdout: ', stdout); console.log('stderr: ', stderr); }) .catch(function (err) { console.error('ERROR: ', err); });
产卵用法
var spawn = require('child-process-promise').spawn; var promise = spawn('echo', ['hello']); var childProcess = promise.childProcess; console.log('[spawn] childProcess.pid: ', childProcess.pid); childProcess.stdout.on('data', function (data) { console.log('[spawn] stdout: ', data.toString()); }); childProcess.stderr.on('data', function (data) { console.log('[spawn] stderr: ', data.toString()); }); promise.then(function () { console.log('[spawn] done!'); }) .catch(function (err) { console.error('[spawn] ERROR: ', err); });
我刚刚写了一个Cli助手来轻松处理Unix/windows.
使用Javascript:
define(["require", "exports"], function (require, exports) { /** * Helper to use the Command Line Interface (CLI) easily with both Windows and Unix environments. * Requires underscore or lodash as global through "_". */ var Cli = (function () { function Cli() {} /** * Execute a CLI command. * Manage Windows and Unix environment and try to execute the command on both env if fails. * Order: Windows -> Unix. * * @param command Command to execute. ('grunt') * @param args Args of the command. ('watch') * @param callback Success. * @param callbackErrorWindows Failure on Windows env. * @param callbackErrorUnix Failure on Unix env. */ Cli.execute = function (command, args, callback, callbackErrorWindows, callbackErrorUnix) { if (typeof args === "undefined") { args = []; } Cli.windows(command, args, callback, function () { callbackErrorWindows(); try { Cli.unix(command, args, callback, callbackErrorUnix); } catch (e) { console.log('------------- Failed to perform the command: "' + command + '" on all environments. -------------'); } }); }; /** * Execute a command on Windows environment. * * @param command Command to execute. ('grunt') * @param args Args of the command. ('watch') * @param callback Success callback. * @param callbackError Failure callback. */ Cli.windows = function (command, args, callback, callbackError) { if (typeof args === "undefined") { args = []; } try { Cli._execute(process.env.comspec, _.union(['/c', command], args)); callback(command, args, 'Windows'); } catch (e) { callbackError(command, args, 'Windows'); } }; /** * Execute a command on Unix environment. * * @param command Command to execute. ('grunt') * @param args Args of the command. ('watch') * @param callback Success callback. * @param callbackError Failure callback. */ Cli.unix = function (command, args, callback, callbackError) { if (typeof args === "undefined") { args = []; } try { Cli._execute(command, args); callback(command, args, 'Unix'); } catch (e) { callbackError(command, args, 'Unix'); } }; /** * Execute a command no matters what's the environment. * * @param command Command to execute. ('grunt') * @param args Args of the command. ('watch') * @private */ Cli._execute = function (command, args) { var spawn = require('child_process').spawn; var childProcess = spawn(command, args); childProcess.stdout.on("data", function (data) { console.log(data.toString()); }); childProcess.stderr.on("data", function (data) { console.error(data.toString()); }); }; return Cli; })(); exports.Cli = Cli; });
打字稿原始源文件:
/** * Helper to use the Command Line Interface (CLI) easily with both Windows and Unix environments. * Requires underscore or lodash as global through "_". */ export class Cli { /** * Execute a CLI command. * Manage Windows and Unix environment and try to execute the command on both env if fails. * Order: Windows -> Unix. * * @param command Command to execute. ('grunt') * @param args Args of the command. ('watch') * @param callback Success. * @param callbackErrorWindows Failure on Windows env. * @param callbackErrorUnix Failure on Unix env. */ public static execute(command: string, args: string[] = [], callback ? : any, callbackErrorWindows ? : any, callbackErrorUnix ? : any) { Cli.windows(command, args, callback, function () { callbackErrorWindows(); try { Cli.unix(command, args, callback, callbackErrorUnix); } catch (e) { console.log('------------- Failed to perform the command: "' + command + '" on all environments. -------------'); } }); } /** * Execute a command on Windows environment. * * @param command Command to execute. ('grunt') * @param args Args of the command. ('watch') * @param callback Success callback. * @param callbackError Failure callback. */ public static windows(command: string, args: string[] = [], callback ? : any, callbackError ? : any) { try { Cli._execute(process.env.comspec, _.union(['/c', command], args)); callback(command, args, 'Windows'); } catch (e) { callbackError(command, args, 'Windows'); } } /** * Execute a command on Unix environment. * * @param command Command to execute. ('grunt') * @param args Args of the command. ('watch') * @param callback Success callback. * @param callbackError Failure callback. */ public static unix(command: string, args: string[] = [], callback ? : any, callbackError ? : any) { try { Cli._execute(command, args); callback(command, args, 'Unix'); } catch (e) { callbackError(command, args, 'Unix'); } } /** * Execute a command no matters what's the environment. * * @param command Command to execute. ('grunt') * @param args Args of the command. ('watch') * @private */ private static _execute(command, args) { var spawn = require('child_process').spawn; var childProcess = spawn(command, args); childProcess.stdout.on("data", function (data) { console.log(data.toString()); }); childProcess.stderr.on("data", function (data) { console.error(data.toString()); }); } } Example of use: Cli.execute(Grunt._command, args, function (command, args, env) { console.log('Grunt has been automatically executed. (' + env + ')'); }, function (command, args, env) { console.error('------------- Windows "' + command + '" command failed, trying Unix... ---------------'); }, function (command, args, env) { console.error('------------- Unix "' + command + '" command failed too. ---------------'); });