How to run a system command from VSCode extension

Your extension environment has access to node.js libraries, so you can just use child_process or any helper libraries to execute commands:

const cp = require('child_process')
cp.exec('pwd', (err, stdout, stderr) => {
    console.log('stdout: ' + stdout);
    console.log('stderr: ' + stderr);
    if (err) {
        console.log('error: ' + err);
    }
});