A command-line interface (CLI) lets you operate software by typing commands and arguments into a terminal. Output returns as text, which makes commands easy to chain, script, and run over a remote connection.
Why it matters
The command line is the standard way to manage servers, run build tools, and call APIs. It is faster to repeat and easier to document than a series of clicks, and it works over SSH when no graphical desktop exists.
Most tools follow a pattern: a command, optional flags, then arguments.
Example
$ curl -I https://example.com
HTTP/2 200Here curl is the command, -I is a flag asking for headers only, and the URL is the argument. The reply shows the status line.
Common mistakes
- Pasting commands from the web without reading them, especially ones using sudo or rm.
- Running destructive commands in the wrong directory; check with pwd first.
- Not using the built-in help, such as
--helporman.
Related
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