Node.js child_process demo. Test for exec(), execFile() and spawn().

childProcess.js

const childProcess = require('child_process');

function execProcess(command) {

    childProcess.exec(command, function(error, stdout, stderr) {

        console.log(`stdout: ${stdout}`);
        console.log(`stderr: ${stderr}`);

        if (error !== null) {
            console.log(`error: ${error}`);
        }
    });
}

function execFile(command, args) {

    childProcess.execFile(command, args, function(error, stdout, stderr) {

        console.log(`stdout: ${stdout}`);
        console.log(`stderr: ${stderr}`);

        if (error !== null) {
            console.log(`error: ${error}`);
        }
    });
}

function spawnProcess(command, args) {

    const s_process = childProcess.spawn(command, args);
    let fullData = '';
    let dataChunks = 0;

    s_process.stderr.on('data', (data) => {
        console.log(`stderr: ${data}`);
    });

    s_process.stdout.on('data', function (data) {
        fullData += data;
        dataChunks += 1;
        console.log(`stdout: ${data}`);
    });

    s_process.stdout.on('end', function () {
        console.log(`end: ${fullData}`);
        console.log(`chunks: ${dataChunks}`);
    });

    s_process.on('close', (code) => {
        console.log(`child process exited with code ${code}`);
    });
}

execProcess('node -v');
// execFile('node', ['-v']);
// spawnProcess('node', ['-v']);

// execFile('ls', ['-l', '/tmp']);
// execProcess('ls -l /tmp');
// spawnProcess('ls', ['-l', '/tmp']);

//----------- the longest article on wikipedia ------------//
// execProcess('curl https://en.wikipedia.org/wiki/List_of_2017_albums');
// execFile('curl', ['https://en.wikipedia.org/wiki/List_of_2017_albums']);
// spawnProcess('curl', ['https://en.wikipedia.org/wiki/List_of_2017_albums']);