Until now, we have mostly run programs in the foreground—typing a command and waiting for it to finish before the shell gives us back the prompt. However, UNIX is a multitasking environment. To be…

A Regular Expression (or regex) is a specialized language used to describe search patterns. While a simple search looks for a specific word, a regex can look for "any word starting with a capital…

In our last module, we explored how to use temporary files to pass data between commands. While functional, that approach was often awkward, inefficient, and, quite frankly, ugly. Today, we learn the…

In our previous sessions, we have been typing commands and seeing the results immediately on the screen. However, in the UNIX world, we say "Everything is a file." This includes your keyboard and…

Vi is often the first "hurdle" for new UNIX users. Because it was designed before the mouse or modern cursor keys were standard, it forces you to think differently about how you interact with text…

Total Weight: 3 Points Objective: Create a robust Bash script that handles user input, validates the file system, and utilizes loops and conditional logic to automate a common administrative task…

Shell Scripting A shell script is essentially a text based file containing a sequence of UNIX commands. To the system, it is a method of writing a program that the shell interprets and executes line…

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…

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…

The Unix Shell: Expansions & Quoting Demystifying how bash transforms your commands before execution   What is the Shell? The shell is a program, a command interpreter. It reads input from…

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…

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…