CLI
also: command line, command-line interface, terminal, shell, console
A Command Line Interface (CLI) is a text-based user interface where you interact with a computer by typing commands instead of clicking a graphical interface.
A CLI lets users control a system by entering text commands at a prompt, typically in a terminal or console window. The system reads your input, executes the corresponding program or operation, and returns text-based output. CLIs are lightweight, scriptable, and powerful for automation.
For example, instead of opening a file manager with your mouse to list files, you type ls at the shell prompt to display directory contents. You can combine commands and redirect output: ls -la | grep .txt lists detailed file information and filters for text files.
Most Linux work happens in the CLI because it offers speed, precision, and the ability to chain commands together using pipes and redirection—features that would be cumbersome in a graphical interface.