Show command output on lockscreen

This started out with me wanting a calendar on the lockscreen. Not a list of events, mind you, but a calendar. You know, the kind that looks like the periodic table of the elements but with day numbers in the boxes and day-of-week down the columns. Currently I open up the terminal and type cal to get this. Then I thought "shouldn't I just be able to put cal on the lockscreen?" More generally, I could make a shell script that would print the calendar and maybe some other nice stuff that suits some whim of the moment, and have that show on the lock screen. Does such an app exist already? I am using the lockscreen that comes with CyanogenMod 11, if that matters.