System Call
Domain: Computer Systems
🎯 Motivation
How programs ask the OS to do things: read files, allocate memory, create processes. The program cannot do these directly.
📋 Concrete Example
System call: open(file.txt) -> OS opens the file and returns a handle. read(handle) -> OS reads data. write(handle, data) -> OS writes data. Programs request, OS executes.
🔗 Analogy
A system call is like ordering food at a restaurant - you (program) tell the waiter (OS) what you want, and the waiter brings it from the kitchen (hardware). You cannot go to the kitchen yourself.