CODEWITHSUNDEEP
node.jschild-process
suamikim
suamikim

Reputation: 5319

Use child_process.execSync but keep output in console

I'd like to use the execSync method which was added in NodeJS 0.12 but still have the output in the console window from which I ran the Node script.

E.g., if I run a NodeJS script which has the following line I'd like to see the full output of the rsync command "live" inside the console:

require('child_process').execSync('rsync -avAXz --info=progress2 "/src" "/dest"');

I understand that execSync returns the output of the command and that I could print that to the console after execution, but this way I don't have "live" output.

Upvotes: 297

Views: 227913

Answers (5)

Ethan
Ethan

Reputation: 3798

You can simply use .toString().

var result = require('child_process').execSync('rsync -avAXz --info=progress2 "/src" "/dest"').toString();
console.log(result);

Edit: Looking back on this, I've realised that it doesn't actually answer the specific question because it doesn't show the output to you 'live' — only once the command has finished running.

However, I'm leaving this answer here because I know quite a few people come across this question just looking for how to print the result of the command after execution.

Upvotes: 62

Axel
Axel

Reputation: 5111

Add {"encoding": "utf8"} in options.

execSync(`pwd`, {
  encoding: "utf8"
})

Upvotes: 3

uzay95
uzay95

Reputation: 16622

Simply:

 try {
    const cmd = 'git rev-parse --is-inside-work-tree';
    execSync(cmd).toString();
 } catch (error) {
    console.log(`Status Code: ${error.status} with '${error.message}'`;
 }

Ref: https://stackoverflow.com/a/43077917/104085

// nodejs
var execSync = require('child_process').execSync;

// typescript
const { execSync } = require("child_process");

 try {
    const cmd = 'git rev-parse --is-inside-work-tree';
    execSync(cmd).toString();
 } catch (error) {
    error.status;  // 0 : successful exit, but here in exception it has to be greater than 0
    error.message; // Holds the message you typically want.
    error.stderr;  // Holds the stderr output. Use `.toString()`.
    error.stdout;  // Holds the stdout output. Use `.toString()`.
 }

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When command runs successful: enter image description here

Upvotes: 10

gregers
gregers

Reputation: 13040

You can pass the parent´s stdio to the child process if that´s what you want:

require('child_process').execSync(
    'rsync -avAXz --info=progress2 "/src" "/dest"',
    {stdio: 'inherit'}
);

Upvotes: 577

Brian
Brian

Reputation: 3334

Unless you redirect stdout and stderr as the accepted answer suggests, this is not possible with execSync or spawnSync. Without redirecting stdout and stderr those commands only return stdout and stderr when the command is completed.

To do this without redirecting stdout and stderr, you are going to need to use spawn to do this but it's pretty straight forward:

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

//kick off process of listing files
var child = spawn('ls', ['-l', '/']);

//spit stdout to screen
child.stdout.on('data', function (data) {   process.stdout.write(data.toString());  });

//spit stderr to screen
child.stderr.on('data', function (data) {   process.stdout.write(data.toString());  });

child.on('close', function (code) { 
    console.log("Finished with code " + code);
});

I used an ls command that recursively lists files so that you can test it quickly. Spawn takes as first argument the executable name you are trying to run and as it's second argument it takes an array of strings representing each parameter you want to pass to that executable.

However, if you are set on using execSync and can't redirect stdout or stderr for some reason, you can open up another terminal like xterm and pass it a command like so:

var execSync = require('child_process').execSync;

execSync("xterm -title RecursiveFileListing -e ls -latkR /");

This will allow you to see what your command is doing in the new terminal but still have the synchronous call.

Upvotes: 26

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