node.js - node的child_process.spawn(...[, options])怎么写多个options?
本文介绍了node.js - node的child_process.spawn(...[, options])怎么写多个options?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
问 题
如果有多个grep,怎么写到上面的语句中?例如cat /dev/urandom |od -x|tr -d ' '|head -n 1
在网上找了下,发现用以下的方法也行,使用spawn
和exec
有什么区别呢?
const exec = require('child_process').exec;
exec('cat /dev/urandom |od -x|tr -d ' '|head -n 1', (error, stdout, stderr) => {
if (error) {
console.error(`exec error: ${error}`);
return;
}
console.log(`stdout: ${stdout}`);
console.log(`stderr: ${stderr}`);
});
解决方案
如果不封装的话,你需要监听多个事件,举例说cat /dev/urandom |od -x|tr -d ' '|head -n 1
const spawn = require('child_process').spawn;
const cat = spawn('cat', ['/dev/urandom']);
const od = spawn('od',['-x']);
const tr = spawn('tr',['-d'," "]);
const head = spawn('head', ['-n',1]);
cat.stdout.on('data', data => od.stdin.write(data));
cat.on('close', (code) => od.stdin.end());
od.stdout.on('data', data => tr.stdin.write(data));
od.on('close', (code) => tr.stdin.end());
tr.stdout.on('data', data => head.stdin.write(data));
tr.on('close', (code) => head.stdin.end());
head.stdout.on('data', data => console.log(`${data}`));
head.stdin.on('error',err=>head.stdin.end());
也可以在spwan创建子进程的时候制定一下pipe管道,比如这样
const spawn = require('child_process').spawn;
const cat = spawn('cat', ['/dev/urandom'], {stdio: 'pipe'});
const od = spawn('od',['-x'], {stdio: [cat.stdout, 'pipe', 'pipe']});
const tr = spawn('tr',['-d',' '], {stdio: [od.stdout, 'pipe', 'pipe']});
const head = spawn('head', ['-n',1], {stdio: [tr.stdout, 'pipe', 'pipe']});
head.stdout.on('data', data => console.log(`${data}`));
head.stdin.on('error',err=>head.stdin.end());
实际环境下,还要处理stderr那边的信息
这篇关于node.js - node的child_process.spawn(...[, options])怎么写多个options?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文