This chapter describes commands which create special types of files (and rmdir, which removes directories, one special file type).
Although Unix-like operating systems have markedly fewer special file types than others, not everything can be treated only as the undifferentiated byte stream of normal files. For example, when a file is created or removed, the system must record this information, which it does in a directory—a special type of file. Although you can read directories as normal files, if you're curious, in order for the system to do its job it must impose a structure, a certain order, on the bytes of the file. Thus it is a “special” type of file.
Besides directories, other special file types include named pipes (FIFOs), symbolic links, sockets, and so-called special files.