allow penalty-free execution of whitelisted shell commands

[filipsch]

@gvwilson commented on Sun May 27 2018

As a user doing a Unix shell course, in consoleExercises I want to be able to run commands like pwd and ls as often as I like without triggering execution of SCTs (influencing submission metrics). After discussion with @filipsch, it seems we could add a whitelist of commands that short-circuit execution of SCTs. These could be provided on a per-exercise, per-chapter, or per-course basis; the last of these three is probably sufficient for everything except the first few chapters of the "Intro to Shell" course (where we definitely don't want these commands short-circuited).

[filipsch]

I would definitely opt for a per-exercise level setup first, as we can just piggy back on top of the SCT with a Ex().whitelist() function that alters the typical SCT execution in some way. Doing things on per-chapter and per-course basis is going to be more tricky.
This will also require backend changes.

[gvwilson]

Is there something like a pre-exercise code block at the chapter level? I suspect that for most chapters, I'll want to whitelist exactly the same set of commands for every exercise.

[filipsch]

@gvwilson no there isn't, that's why this would be so hard.

[gvwilson]

Understood.