What Happens During a read() System Call
The video follows read(fd, buffer, count) through a Linux-oriented path. The drawing marks the privilege transition, descriptor lookup, virtual file-system dispatch, and the two branches where bytes are already cached or the task waits for I/O. It explains that read may return fewer bytes than requested and that a descriptor is a process-local handle.
The lesson ends with three different outcomes: a byte count, end-of-file, or an error. Kernel-version and file-type variation are called out instead of being hidden behind one universal diagram. Companion material: system-call article, read trace, and the Linux manual page.
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