Run a command within an existing shell window from a second shell window

Question

I have a program that is running on a shell window. I would like to input command into that shell (using a script) to make the program behave in a certain way. What would be the command to send a command from one shell to another.

Thank you

Answer 1

the answer i was looking for was

xdotool

you can use to search a window (xdotool search), run a command (xdotool key)