You should perhaps realize how it is possible to paste text into a window. I am talking about a console window, that is a CLI running inside a window initiated from a GUI.
If you copy text from somewhere, and paste it into the console, the GUI environment knows that the paste command involves simulating keypresses into that console. Your CLI application is totally unaware that something is pasted, it just sees the keystrokes being generated by the paste command.
So if you want to paste something in a CLI environment, NOT running in a GUI window, you have to be sure that the CLI application KNOWS what it is to get something pasted. Usually that is pretty much impossible.