The yum history command displays list of all commands used to install or remove packages using yum package manager. The list is ordered by date and id. Each history item is called a transaction.
HTTPS Certificates are files that are used to secure websites. A website that is secured using HTTPS is accessed using the HTTPS protocol. For example https://www.google.com. HTTPS certificates are issued by a Certificate Authority (CA). Lets Encrypt is a CA that issues HTTPS certificates free of cost.
The Ionic Framework allows developing applications for web browsers, desktops and mobile devices. Ionic Framework applications are written in HTML, CSS and JavaScript. Apps can be generated from a single code base, which can be accessed from web browsers, Android, IOS and Windows based devices.
If your website is based on PHP and is being served by Apache web server with Nginx as reverse proxy, then you may have experienced 504 Gateway Timeout errors. The error usually happens because some PHP script takes longer than usual to run.
Jekyll is a static site generator. It generates static HTML pages from content written in Mark Down or HTML. Its different from other website publishing tools in that it does not use a database.