Passing URL parameters as command line script arguments security considerations

I am writing a web app and I need to pass some url parameters as command line arguments to another script. What should I do to avoid security problems? I am using Sympfony's Process to execute the bash command and Laravel to build the app.

Here is some of the code, look into the buildScreenshotCommand to see how I am building the command string and also note that the $urlRequest is filled in using the Laravel's Request $request class:

<?php

namespace App\Logic;

use App\Logic\TimeHelper;
use App\UrlRequest;
use Illuminate\Support\Facades\Storage;
use Symfony\Component\Process\Exception\ProcessFailedException;
use Symfony\Component\Process\Process;

class Screenshot {

    static function take(UrlRequest $urlRequest)
    {
        $name = self::generateName($urlRequest);
        $command = self::buildScreenshotCommand($name, $urlRequest);

        $startTime = TimeHelper::milliseconds();

        $process = new Process($command);
        $process->run();

        $endTime = TimeHelper::milliseconds();

        if (!$process->isSuccessful())
        {
            throw new ProcessFailedException($process);
        }

        $output = $process->getOutput();

        if (trim($output) === '')
        {
            $urlRequest->successful = 1;

            $file = self::uploadToS3($name);
            $urlRequest->image_url = $file['url'];
            $urlRequest->file_size = $file['size'];
            $urlRequest->file_name = $name;
            $urlRequest->time_it_took_to_take_screenshot_ms = $endTime - $startTime;

            if ($urlRequest->save())
            {
                return $urlRequest;
            }
        }
        else
        {
            $urlRequest->error = $output;
            $urlRequest->save();
        }

        return false;
    }

    static function uploadToS3($name)
    {
        $name = 'screenshots/' . $name;

        Storage::disk('s3')->put($name, Storage::disk('local')->get($name), ['visibility' => 'public']); // upload to S3

        $fileSize = Storage::disk('local')->size($name);
        Storage::disk('local')->delete($name);

        return [
            'url' => Storage::disk('s3')->url($name),
            'size' => $fileSize
        ];
    }

    static function generateName($urlRequest)
    {
        $name = time() . rand(10000, 99999);
        $extension = '.png';

        if (isset($urlRequest->pdf) AND $urlRequest->pdf == 1)
        {
            $extension = '.pdf';
        }

        while (UrlRequest::where('file_name', '=', $name . $extension)->first())
        {
            $name = time() . rand(10000, 99999);
        }

        return $name . $extension;
    }

    static function buildScreenshotCommand($name, $urlRequest)
    {
        $command = 'cd ' . base_path() . ' && node puppeteer-screenshots-init.js ';
        $command .= "--url={$urlRequest->url} ";

        $fullPath = storage_path('app') . '/screenshots/' . $name;

        $command .= "--path={$fullPath} ";

        if (isset($urlRequest->pdf))
        {
            $command .= "--pdf=true ";
        }

        if (isset($urlRequest->viewport_width))
        {
            $command .= "--viewportWidth={$urlRequest->viewport_width} ";
        }

        if (isset($urlRequest->mobile))
        {
            $command .= '--mobile=true ';
        }

        if (isset($urlRequest->media_type_print))
        {
            $command .= '--mediaTypePrint=true ';
        }

        if (isset($urlRequest->user_agent))
        {
            $command .= '--userAgent="' . $urlRequest->user_agent . '" ';
        }

        $command .= '2>&1 &';

        return $command;
    }

}

via Chebli Mohamed