Mastering the Command-Line Interface (CLI)

The command line shell is where nearly everything on a Linux system happens, and nearly everything that happens at the command line involves manipulating text in one way or another. This course focuses on using command-line tools to work with plain-text data — whether that data lives in files or is moving between processes and destinations. All demonstrations run against a Linux system operating inside a container, which behaves exactly like a physical machine for the purposes of these commands.

Using ls to list the contents of an empty directory named project shows nothing, since there is nothing there to display yet. The -l flag would normally provide a long listing with ownership, permissions, size, and timestamp information, but with an empty directory there is nothing extra to show.

After typing some simple content, Ctrl+X saves the file and exits nano. Listing the directory again shows newfile present, owned by the current user and group, along with the date and time it was last updated.