This book explores system administrator fundamentals. These days, DevOps has made even the job title “system administrator” seem a bit archaic, much like the “systems analyst” title it replaced. These DevOps positions are rather different from typical sysadmin jobs in the past in that they have a much larger emphasis on software development far beyond basic shell scripting. As a result, they often are filled with people with software development backgrounds without much prior sys- admin experience. In the past, sysadmins would enter the role at a junior level and be mentored by a senior sysadmin on the team, but in many cases currently, companies go quite a while with cloud outsourcing before their first DevOps hire. As a result, DevOps engineers might be thrust into the role at a junior level with no mentor around apart from search engines and Stack Overflow posts. In this book, I expound on some of the lessons I’ve learned through the years that might be obvious to longtime sysadmins but may be news to someone just coming into this position.