CODEWITHSUNDEEP
javascriptnode.jschild-process
Malintha
Malintha

Reputation: 4776

Passed argument to the child process is undefined

I am running a script inside a script using child_process.fork(). I am using a variable (an instance of another application) inside my main script and I need to pass this as an argument to the subsequent script to get it updated there. I tried it following way

Sub script

console.log(process.data);
let a = process.data;
.....................

Main script

function runScript(scriptPath, data, callback) {

    var invoked = false;
    var process = childProcess.fork(scriptPath, data);

    process.on('error', function (err) {
        if (invoked) return;
        invoked = true;
        callback(err);
    });

    process.on('exit', function (code) {
        if (invoked) return;
        invoked = true;
        var err = code === 0 ? null : new Error('exit code ' + code);
        callback(err);
    });

} 

 let dataValues = "this from the main script";

 runScript('./subscript.js' ,dataValues, function (err) {
      if (err) throw err;
      console.log('finished running some-script.js');
 });

I am getting undefined when I try to access the argument from the subsequent script. Seems like the argument is not sent to the subsequent script. It was running as expected if I don't pass arguments to the second script.

What is the issue with the way of my data sending to the subsequent script?

Upvotes: 0

Views: 502

Answers (2)

Fabian Lauer
Fabian Lauer

Reputation: 9907

.fork(...) expects a string[], not astring (docs), so try passing the arguments as an array:

let dataValues = ["this from the main script"];

Also, in the child process, you will receive the arguments in the process.argv array, not process.data. Try this for in child process script:

console.log(process.argv);

Upvotes: 1

Rajan Lagah
Rajan Lagah

Reputation: 2528

You can send args as command line arguments to your second script like 

childProcess.fork(scriptPath+" "+data); //data can be a1 a2 a3

and then on your script (scriptPath) you can access them by process.argv

for (let j = 0; j < process.argv.length; j++) {  
    console.log(j + ' -> ' + (process.argv[j])); 
}

// output will be 

0 -> a1
1 -> a2
2 -> a3

Upvotes: 0

Related Questions