Let's Encrypt is "a free, automated, and open Certificate Authority." They provide free signed certificates as a trusted certificate authority. This tutorial walks through the process of installing certbot and requesting new certificates and renewing existing ones wit Let's Encrypt. If you are just looking to generate your own quick self-signed certificates, check out my tutorial on creating self-signed SSL certificates with OpenSSL.
It is possible to write GTK2 application using PHP. It is a little work to get it compiled and installed, but once configured it is easy to write programs with GTK2. As of June 22, 2015 a development branch has been created for GTK3. Follow these installation instructions first. Then try out the code samples below. Load the php-gtk2 module in your php.ini as well.
PHP Simple HTML DOM is a one-file library that lets you traverse the elements of an HTML and search for specific elements. The examples below show how to use this library. To learn how to crawl (or spider) websites in order to get many pages to process see this post on How to Crawl Web Pages with PHP
Uwe Hunfeld provides an object oriented library called PHPCrawl available at http://phpcrawl.cuab.de. This class can be used to crawl web pages with many different parameters. It also allows you to process each page and do what manipulation or scraping you need to do. You accomplish this by overriding the base class and implementing your own functionality in the handleDocumentInfo() and handleHeaderInfo() functions. Use the code below as an example of how to create your own web crawler. If you want to learn how to parse the HTML DOM and extract things like links and headings, check out the post on How to Parse HTML DOM with PHP.
PHP/TK implements object oriented bindings for TCL/TK that can be used to create GUI applications. It only works on Unix systems. PHP must be configured to allow dynamic linking with enable_dl = On in the php.ini. The shared object file (tk.so) can be downloaded manually from PECL. The shared object file goes inside your php modules folder which is typically something like /usr/lib/php/modules. Look for the folder with other .so files or refer to your particular distribution documentation.
SQLite is a relational database that stores data in memory or in a single portable file. These code snippets demonstrate how to use SQLite with PHP. One thing to note about exec verus query: the first executes a result-less query, and the latter performs a query that returns results. It is better to use a prepared statement than a query though. It is easier, safer, and will use less memory.
This code will allow you to tail a file in PHP. It is cheating a little bit though because it is actually making a system call to tail, so you have to have tail installed. It is meant for Linux machines not Windows.
cURL is a great library for transferring data over a number of network protocols. Unfortunately, it can be a little overwhelming to use for the first time in PHP and there are lots of options available. Here is an easy reference for using cURL in PHP.
In PHP, all command line arguments, including the script name itself are stored in a special array named $argv. The first element, zero, is the name of the script being run. For example: