Node.JS wait for node-cmd run command to finish before starting other command

Question

I am currently developing a program where you can create virtual machines in VirtualBox as a project. To do this I need to run 2 commands synchronously as one creates a VM and the other modifies that VM. Here is the code.

nodecmd.run(cmd);
var cmd1 = createCmd1.concat(createServ);
console.log(cmd1);
var cmd2 = cmd1.concat(' --natpf1 "ssh,tcp,,302');
console.log(cmd2);
var cmd3 = cmd2.concat(createServ);
console.log(cmd3);
var cmd4 = cmd3.concat(',,22"');
console.log(cmd4);
nodecmd.run(cmd4);

Thanks!

This depends a lot on whatever nodecmd is and how it would return child processes. — Brad
– Brad, Commented Feb 22, 2019 at 14:04
I am a complete beginner please may you explain what a child process is please? — Toffee
– Toffee, Commented Feb 22, 2019 at 14:07
I have completed what I need to do now with child processes. Thanks! — Toffee
– Toffee, Commented Feb 22, 2019 at 14:17

Toffee · Accepted Answer · 2019-02-22 14:19:02Z

3

I have found that I can just use child processes:

const execSync = require('child_process').execSync;
code = execSync('node -v');

answered Feb 22, 2019 at 14:19

Toffee

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Ashvin777 · Accepted Answer · 2019-02-22 14:18:21Z

1

I think you should use promise to chain your executions steps. Promises are good for handling asynchronous chaining events.

node-cmd support promise using bluebird.

const promise = require('bluebird');
const nodecmd = require('node-cmd');

const getAsync = promise.promisify(nodecmd.get, {
    multiArgs: true,
    context: nodecmd
});

let cmd0 = 'node -v';
let cmd1 = 'pwd';
let cmd2 = 'mkdir -p xxx';

getAsync(cmd0)
    .then(result => console.log(result))
    .then(() => getAsync(cmd1))
    .then(result => console.log(result))
    .then(() => getAsync(cmd2))
    .then(result => console.log(result))
    .catch(err => {
        console.log('cmd err', err)
    })

Try this in action - https://jsitor.com/2ZZPZqtvb

answered Feb 22, 2019 at 14:18

Ashvin777

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3 Comments

Toffee Over a year ago

I just realised that node-cmd was probably created to use commands asynchronously. I have upvoted but it doesn't show because I don't have 15 rep.

Ashvin777 Over a year ago

Yes, I agree but you can use it along with the promises to execute it in sync.

sathyam1992 Over a year ago

Thanks, this helped me come out of a messy work around (sleeping for minutes before moving to next step).

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