In our previous sessions, we took a “side trip” into the life-cycle of a UNIX process. We learned about forking, exec-ing, and the parent-child relationship. Why? Because without understanding how processes are born, you cannot understand Environment Variables. 1. Local Variables vs. Environment Variables In the shell, we have two distinct types of variables: Shell… View Article

In our previous sessions, we explored the static world of files and permissions. Today, we move into the dynamic world of the UNIX Kernel. If the file system is a library, then a process is a person currently reading a book. One is storage; the other is action. 1. What exactly is a Process? A… View Article

The Logic of UNIX File System Permissions In UNIX, security is not an afterthought, it’s built directly into the file system structure. Every file and directory is governed by a set of “modes” that dictate exactly who can read, write (modify), or run it. 1. The “Three by Three” Rule UNIX permissions are organized into… View Article

The UNIX File System, Part 2 To recap last week’s lecture, a file system’s primary job is to manage data storage on random access devices using a hierarchical structure. Today, we will move beyond just “where” files are and look at “what” they actually are. 1. Pathfinding Review Before we dive into the guts of… View Article

        Understanding the UNIX File System In the first class we discussed the “heart” of UNIX, that being the kernel. The “voice” that being the shell which allows you to speak to the OS. Today we will look at the filing cabinet. Enter The UNIX file system. This is what manages, stores… View Article

    Week 1 – Foundations of UNIX – Written by Anthony Adams Welcome to Fundamentals of UNIX. To understand modern computing, you have to understand UNIX. Whether you use a Mac computer, android phone, Ubuntu, Fedora, Arch or are just browsing the web (which for the most part servers run on Linux) You are… View Article