整理以前的笔记，围绕Linux下的I/O模型，主要介绍了阻塞IO、非阻塞IO、IO多路复用、信号驱动IO和异步IO等模型的工作原理和适用场景。

🤖 Explores Linux file system architecture built on Unix's "everything is a file" philosophy, covering VFS layer, popular file systems (ext2/3/4, XFS), and how files exist differently in disk vs kernel through superblocks, inodes, and file descriptors. Learn practical file descriptor usage with hands-on examples.