A free, self-paced textbook in 7 chapters. Read a chapter, then drill it with the 51 companion flashcards using spaced repetition.
The Linux command line interface (CLI) is a text-based environment for interacting with the operating system by typing commands into a terminal emulator. Unlike a graphical user in...
Linux organizes files in a single hierarchical tree rooted at /. To understand where you are at any moment, the pwd (Print Working Directory) command shows the absolute path of you...
Inspecting the contents of files is a frequent task. cat filename concatenates and prints the whole file to the screen, which is fine for short files but unwieldy for large ones. P...
Every file and directory in Linux carries a permission set that controls who can read, write, or execute it. These permissions appear in the output of ls -l as a string like rwxr-x...
Linux exposes the running programs on your system through processes. ps aux provides a snapshot of every process with details such as the owning user, CPU usage, and memory consump...
Linux distributions ship with package managers that handle installing, updating, and removing software. On Debian-based systems such as Ubuntu, apt update refreshes the local index...
Combining many files into a single archive and then compressing them is a common task. tar is the traditional Unix archiver: tar -cvf archive.tar dir creates an archive (the c is "...