Summary
This chapter provided an introduction to file I/O based system calls. It is important to grasp these concepts before trying to understand how filesystems are implemented. By understanding what the user expects, it is easier to see how certain features are implemented and what the kernel and individual filesystems are trying to achieve.
Whenever programming on UNIX, it is always a good idea to follow appropriate standards to allow programs to be portable across multiple versions of UNIX. The commercial versions of UNIX typically support the Single UNIX Specification standard although this is not fully adopted in Linux and BSD. At the very least, all versions of UNIX will support the POSIX.1 standard.
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