A free, self-paced textbook in 8 chapters. Read a chapter, then drill it with the 110 companion flashcards using spaced repetition.
The Linux shell becomes powerful when its small utilities are combined with pipes and redirection. The command ls lists directory contents and accepts flags such as -l for long for...
Linux organizes the entire system under a single hierarchical tree rooted at /. A few top-level directories deserve attention: /etc holds system-wide configuration such as /etc/pas...
Every running program on Linux is a process identified by a PID, and operators routinely need to inspect, signal, and reorder them. The ps command produces a static snapshot: ps au...
User and group administration underpins access control. New accounts are created with useradd -m -s /bin/bash john (the -m flag provisions a home directory), passwords set with pas...
Modern Linux configures networking through the ip suite, which supersedes the older ifconfig and route. ip addr show lists addresses and their interfaces, ip link show enumerates l...
Disk management starts with discovery. lsblk lists block devices in a tree (disks, partitions, and their mount points), and lsblk -f adds the filesystem type and UUID. df -h report...
Bash scripts glue the system's utilities together, and mastering variables, control flow, and exit handling unlocks real automation. Variables are assigned without spaces around =...
Observability starts with what the kernel exposes. The traditional ring buffer holds boot and runtime messages that dmesg can dump (dmesg -T for human timestamps, dmesg -w to follo...