[FEATURE] Setting environment variables outside of `.nbrc`

[Beethoven-n]

I ran into a bit of an issue while testing nb show's options.
There's a --browse option, but it only uses $NB_BROWSER, which I've set to a TUI browser. I have a GUI browser at $NB_GUI_BROWSER, but I can't use it for this.
My thought was that I'd be able to just do NB_BROWSER=$NB_GUI_BROWSER nb show $id -b, but it seems .nbrc overrides the value I set.

Slightly unrelated, but I also tested this in nb shell and found I wasn't able to set them at all there.

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nb shell started. Enter ls to list notes and notebooks.
Enter help for usage information. Enter exit to exit.
nb❯ NB_BROWSER=librewolf
! Not found: NB_BROWSER=librewolf
nb❯

maybe this is down to .nbrc encouraging you export your variables instead of just setting them? idk 🤷

[xwmx]

You can make an assignment overridable using parameter expansion:

export NB_BROWSER="${NB_BROWSER:-example}"

In this example, $NB_BROWSER is assigned to the existing value of $NB_BROWSER if one has already been set, and if $NB_BROWSER is unset, then $NB_BROWSER is assigned the value "example". If you include the assignment in this format within ~/.nbrc, then the value assigned when you call the command with NB_BROWSER=sample nb show 11 -b should override the value set in ~/.nbrc.

Regarding NB_BROWSER=$NB_GUI_BROWSER nb show $id -b, I just added an undocumented -g / --gui option that can be used as nb show --browse --gui to open an item in the GUI browser via show if that's the functionality you are looking for. It looks like the code related to this could probably be condensed and refactored a little, but I'll have to revisit it when I have a little more time.

[Beethoven-n]

ah, i always wish that was expressed a bit more readable...
i'll have to explain it with some comments so i remember what it means if i forget. that will work though.
thanks for the extra option!

[Beethoven-n]

oh, right. about setting vars in nb shell. should that even be a thing? it feels like it should, since it's a shell itself