This is the third video from a cycle devoted to system programming and operating systems.
In this part, I discuss details of filesystem trees and forests. Typical file operation (open/read/write/close) are described on demo programs as well as more interesting actions (file mapping and locking and arbitrary I/O calls). I systematize approaches to increasing I/O efficiency and demonstrate speed of I/O in different languages. Timers, terminals, and pseudoterminals are described and their usage is shown on sample C programs. Finally, I discuss principles of X Window System architecture.