看英文,不要看中文, 另外要看完.(下面的英文应该让你更好懂)
Files are logical units of information created by processes. A disk will usually
contain thousands or even millions of them, each one independent of the others. In
fact, if you think of each file as a kind of address space, you are not that far off, except
that they are used to model the disk instead of modeling the RAM.