The VFS

In the previous article we saw how the scheduler decides which task gets the CPU — so at this point we know how programs get to run. But running isn’t enough: for a program to be useful, it almost always needs to read and store data — its config from /etc, a shared library from /usr/lib, the rows of a database file, the document you’re saving. So the natural next question is: what actually happens when a program opens a file?