For simplicity, everything in UNIX and Linux-based operating systems is treated as a file. Files in the filesystem are arranged in a hierarchical tree like a structure with the root of the tree denoted by '/' (forward slash). A node of the tree is either a directory or file where the directory is also a special type of file containing inode numbers and a corresponding filename entry of the list of files inside it. An inode number is an entry in an inode table that contains metadata information related to the file.

In this chapter, we will take a closer look at the important and commonly used file types. We will see how we can create, modify, and perform other useful operations on files. We will also see how to monitor a list of files opened by a process or user.

This chapter will cover the following topics in detail: