How to make a "command line basd" interactive program?

[Evan]

Hope this hasn't been posted hundreds of times. I'm new for this.

Before using python for this kind of script, I was using TCL to write
down a "command line based" interactive program.  it likes a "tclsh",
or "python" command, after that, you can work under a prompt,  for
example, " - >> ", and then you can execute any commands what you
defined in script.

Now, in python, are there any common way(class) to finish this work?
or does anybody has a example to do that?

Thanks,
Evan