Send commands to different user on same machine

I currently have a separate user account on my machine that just runs a bunch of stay-on scripts. I can fast user switch to this account to check progress and such, but is there any way to send commands to the applications/scripts running on this account from my main account that is also logged in? I have seen lots of tips on how to send commands to other machines, but none on how to address other accounts on the same machine.
Thanks in advance