In this hour, you learn
What a hierarchical file system is all about
How the UNIX file system is organized
How Mac and PC file systems differ from UNIX
The difference between relative and absolute filenames
About hidden files in UNIX
About the special directories “.” and “..”
About the env command
About user environment variables, PATH and HOME
How to find where you are with pwd
How to move to another location with cd
The preceding hour introduced a plethora of UNIX commands, but this hour takes a more theoretical approach, focusing on the UNIX file system, how it's organized, and how you can navigate it. This hour focuses on the environment that tags along with you as you move about, particularly the HOME and PATH variables. After that is explained, you learn about the env command as an easy way to show environment variables, and you learn the pwd and cd pair of commands for moving about directly.