Lesson 1 of 6 · About 6 minutes
What an operating system does
Learn the concept.
Your apps need memory, processor time, files, and devices. The operating system coordinates that work and enforces many of the boundaries between users and programs.
A file request travels through the system
Follow the sequence, or move one step at a time.
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Read all 4 steps
- Ask for the file
The application asks to open a file on behalf of the current account.
- Check the boundary
The operating system evaluates access under its security model.
- Read the content
If access is permitted, the system reads the requested content.
- Return the result
The application receives content or an error. A request is not automatically an allowed read.
Three layers, different jobs
Opening a file is a useful example.
- Application
Requests access to a file.
- Operating system
Checks access and manages the read.
- Hardware
Storage provides the requested bytes.
Read the visualWhat coordinates memory, files, and processor use for running applications?
The operating system provides and manages resources that applications use. A desktop or terminal is an interface to parts of that system.
Separate the layers
Hardware is the physical equipment. The operating system manages its use. Applications ask the operating system for services, such as opening a file.
Know which environment you are using
Windows, macOS, and Linux share many concepts but use different tools and conventions. Our practice terminal models a small Linux environment; its output is fictional.
A window is not the whole computer
A graphical desktop and a command-line shell are ways to interact with a system. A terminal is a text interface; the shell interprets commands. Closing one window does not necessarily stop background work.
Put it in context
At Harbor Books, a browser and a backup service run on the same workstation. The browser has a visible window; the backup service does not need one. Both still rely on the operating system.
Make a decision.
Explore the practice space, then answer the check-in below. A correct answer lets you save this lesson to your progress.
YOUR PRACTICE SPACE
Try the idea for yourself.
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Take this with you.
Identify the system and the account before interpreting what a tool tells you.
Next lesson: Files, folders, and paths