🐧 Linux

What you can learn on this page

• 🎯 What is Linux, and why does a QA engineer need it? — Linux is the operating system running beneath almost every CI agent, Docker container, Kubernetes node, and cloud VM you will ever touch as a QA engineer — not as a visible surface, but as the invisible load-bearing wall the whole building stands on. But here
• ⚙️ Getting a Linux Environment — WSL2 (Windows Subsystem for Linux 2) is not a simulator or an emulator — it runs a genuine Linux kernel inside a lightweight VM right alongside Windows, the same way Docker Desktop does it under the hood. Think of it like a flight simulator that uses a real ai
• 📁 Filesystem & Navigation — The Linux filesystem is a single upside-down tree rooted at `/` — every file, every device, every mounted volume hangs from that one root, with no `C:` or `D:` drive letters anywhere. But here is the question that trips up Windows and Java developers alike: if
• 🔐 Permissions & Users — Linux file permissions are a three-audience access control system: every file has exactly three answers to "who can do what" — for the owner, for anyone in the same group, and for everyone else — and each answer is three bits: read (r), write (w), ex
• 📝 Text & Pipes — The Linux pipe (`|`) connects the standard output (stdout) of one process directly to the standard input (stdin) of the next, building a data-processing pipeline from small, single-purpose tools without any intermediate files. Think of it the same way Java's S
• ⚙️ Processes & Services — Every running program on Linux is a process — an isolated unit with its own PID (process ID), memory space, file descriptors, and signal handlers — and the OS scheduler hands each one CPU time in turn, just as Java's JVM schedules threads. But here is the ques
• 🧪 Real-World QA Scenarios — Debugging a failing CI pipeline on a live Linux agent is like performing surgery on a running engine — the system cannot be stopped, the environment cannot be changed, and every action you take might make things worse if you misdiagnose. The real-world QA scen
• 🔗 Ecosystem — Linux is not just one tool in the QA ecosystem — it is the shared kernel that every other tool in your stack is built on top of. Docker containers share the host's Linux kernel. Kubernetes nodes run Linux. GitHub Actions `ubuntu-latest` runners are Linux VMs.