This chapter will be focusing on Unix OS and on the components that the user will interact with: files and filesystems, processes, users and permissions, and so on. It will also explain some basic process communication and how system program error handling works. All these parts of the operating system will be the ones we will be interacting with when creating system applications. 

The following topics will be covered in this chapter:

• Memory management
• Files and filesystems
• Processes
• Users, groups, and permissions
• Process communications