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Although Ubuntu is a desktop-driven OS, the system is running on a powerful and incredibly flexible command-line core. Inspired by more than 30 years of UNIX heritage, the command-line environment present on Linux systems enables you to perform some incredibly powerful tasks by stringing together different commands in different ways.
The philosophy behind UNIX is to create a large number of small tools, each of which is designed to do one task but do it incredibly well. As a quick example to whet your appetite, there is a command called ls that does nothing more than list files in a folder. Although listing files is its singular function in life, it has every option imaginable for listing files.