The GET command is not a built-in command in most command-line interfaces, including the default command-line shell on most Unix-like operating systems (e.g. Bash). It is, however, a common HTTP method used in web development.
In a web context, the GET method is used to request data from a server. When a client (such as a web browser) sends a GET request to a server, the server responds with the data that the client has requested. For example, if a user enters a URL into their web browser, the browser will typically send a GET request to the server hosting the website to retrieve the HTML, CSS, and other resources needed to render the page.
If you are trying to use the GET command in a command-line interface and are getting a "command not found" error, it is likely that you are confused about the difference between HTTP methods and command-line commands. HTTP methods like GET, POST, and PUT are used in web development to specify the action that a client is requesting from a server. In contrast, command-line commands are used to perform various tasks on the local computer or on a remote server using the command-line interface.