From navigation and file management to permissions, processes, networking, package management, and shell scripting for working confidently in any terminal.
pr, lpr, and lp cover the three stages of printing on Linux: pr formats text for a page, lpr and lp send files to a printer. lpr is the Berkeley-style command; lp is the System V-style command. Both talk to CUPS — the Common UNIX Printing System that almost every Linux distro uses today. Key…
These three commands are the print management trio on Linux. lpstat tells you about the printers — which ones exist, which are accepting jobs, which is the default. lpq shows you the queue — what’s waiting to print. lprm lets you remove jobs from the queue. Key point: All three work with CUPS (Common UNIX…
A shell script is a plain-text file full of shell commands that the system runs for you, in order, automatically. Instead of typing the same sequence of commands over and over, you write them once and run the script. It’s the simplest form of programming on Linux — and one of the most useful. Key…
Variables are the foundation of any shell script. They let you store values, pass data around, and make your scripts flexible instead of hardcoded. Shell scripts also come with a set of special variables that the shell fills in automatically — the script name, arguments, process ID, and exit status. Key point: In shell scripting,…
Outputting text is the most basic thing a shell script does. You can use echo for simple messages, printf when you need precise formatting, and here documents when you need to pass a block of multi-line text to a command. Key point: echo is quick and convenient but behaves differently across shells. printf is predictable…
56 – shell scripts input text The read command is how a shell script asks the user for input. It reads a line from standard input (usually the keyboard), splits it into fields, and assigns them to variables. With a few options, it can prompt, hide input, read a fixed number of characters, or time…
Functions let you encapsulate code into reusable blocks. Instead of repeating the same commands in several places, you define them once and call them by name. This makes your scripts cleaner, shorter, and easier to maintain. Key point: Shell functions are not like functions in C or Python. They don’t have a return type, they…
Part 1 covered how to define and call functions. Part 2 is about making them robust — how functions report success or failure, how to stop a script when something breaks, and how to catch errors before they cascade. These techniques separate a fragile script from one you can trust in production. Key point: In…
59 – shell functions flow control and if Flow control is what turns a script from a straight line of commands into a program that makes decisions. The if statement is the most important of these — it lets you run different code depending on whether a condition is true or false. Combined with operators…
The test command is the engine behind every if condition you’ve written so far. [ … ] is actually a synonym for test — they do exactly the same thing. Understanding test directly makes your scripts clearer and helps you avoid quoting bugs. Key point: test evaluates a conditional expression and returns an exit status…