Goals for this Hour

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.