OS

Operating Systems

advanced

The program that runs all your programs.

The OS is the layer between your code and the hardware: it decides which program runs when, hands out memory, turns 'open this file' into disk operations, and keeps processes from trampling each other. Every language and every app sits on these ideas — processes, threads, files, system calls. Learn them once, understand computing forever.

Systems ProgrammingDevOps & ServersDebuggingPerformanceCS Fundamentals
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0/7 lessons

Setup

Concepts track — nothing to install. The best lab is a Linux shell: WSL on Windows, Terminal on macOS, or any Linux box. Commands below let you watch your OS work in real time.

Bash
# Install WSL (a real Linux kernel inside Windows):
wsl --install

# Then inside WSL, watch the OS at work:
ps aux          # every process
top             # live process view
free -h         # memory usage

Lessons

1
What an OS Actually Does
Strip away the desktop and wallpaper: an operating system is a resource manager …
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2
Processes
A process is a running program plus everything it owns: its memory, its open fil…
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3
Threads & the Scheduler
Your machine runs 400 processes on 8 cores. The illusion that they all run 'at o…
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4
Memory: Virtual, Paged, Shared
Every process believes it has the entire address space to itself. It's lying — o…
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5
Files, Descriptors & Filesystems
Unix's boldest simplification: everything is a file. Documents, your terminal, n…
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6
System Calls & Talking Between Processes
Every interesting thing a program does — print, read a file, open a connection —…
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7
OS Cheatsheet
Processes, memory, files, and the commands to inspect them — one page.
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