We now start to look in earnest at the system call API. Files are a good place to start, since they are central to the UNIX philosophy. The focus of this chapter is the system calls used for performing file input and output.
We introduce the concept of a file descriptor, and then look at the system calls that constitute the so-called universal I/O model. These are the system calls that open and close a file, and read and write data.
We focus on I/O on disk files. However, much of the material covered here is relevant for later chapters, since the same system calls are used for performing I/O on all types of files, such as pipes and terminals.
Chapter 5 extends the discussion in this chapter with further ...