Add quarto check environment-variable as a way to verify which read-only env var is set and will be used by Quarto

[cderv]

Quarto has now a few environment variable read in to modify behavior. We document them on
https://quarto.org/docs/advanced/environment-vars.html#variables-quarto-inspects

It would make sense to have a way to check value set with quarto check
Could be one of:

• quarto check environment
• quarto check environment-variables

[roaldarbol]

I think this is a great idea. :-) Why not just include them in quarto check? That way it'll be easier to report for issues (only needing the output from quarto check). It's not that many env variables in the end.

[mcanouil]

That's the point of the issue, check quarto check --help.
quarto check is quarto check all.

• quarto check install
• quarto check jupyter
• quarto check knitr
• quarto check all

[roaldarbol]

Ah, it just sounded to me like they would only be shown when environment or the variable (e.g. chromium) was appended. But sounds good to me. :-)