You won't find that kind of app from apples store, would have to root it to get a real command prompt. I remember around y2k getting the serial adapter for my windows ce 2.1 and using it to setup cisco routers using a simple terminal program.

The unfortunate thing about apple's products is they set the bar of the industry so newer releases of other products loose features because the apple's products don't have those features. Windows CE/Windows mobile lost a lot of the actual pim features over the years and it seems the newer palm doesn't have near the abilities as some of the old. Thats why I've switched over to open source because you at least have some hope of getting missing features implemented.