bug#60566: [PATCH] environment: Fix '--emulate-fhs' option overriding $PATH.

[John Kehayias]

Hi Ludo’,

On Sat, Jan 07, 2023 at 12:03 AM, Ludovic Courtès wrote:

> To be safe, you need to account for (getenv "PATH") returning #f, and
> not add a trailing colon in that case.
>

Ah, right. I think this would only happen if somehow unsetting PATH and 
preserving it? As 'guix shell' already sets PATH. Anyway, better to be safe 
here.

I tweaked this, though not sure if there is a more elegant way to construct the 
string than what I did (suggestions always welcome!).

> Other than that, I agree this is a valid change because that would be
> consistent with:
>
> $ PATH=/foo $(type -P guix) shell -E ^PATH$ -C coreutils -- env |grep ^PATH
> PATH=/gnu/store/pfl0lyqbs557khv7rw90bzp24qp2lqsn-profile/bin:/foo
>
> Perhaps you can add a line to test it in
> ‘tests/guix-environment-container.sh’?
>

I added two tests while I was at it: one to check that PATH has the FHS 
modification in the container and a second for this particular bug. For the 
second one I just used a test string added to PATH as the entire thing will 
differ already from inside/outside the container, FHS or not. I checked the 
tests pass here and removing '--emulate-fhs' causes the first to fail while 
removing the '--preserve' argument causes the second test to fail. I could 
separate the first out as a separate commit if that makes more sense, but I do 
think the current behavior is just wrong in overwriting all of PATH when 
'--emuate-fhs' is given.

New version attached, thanks for the suggestions!

John

0001-environment-Fix-emulate-fhs-option-overriding-PATH.patch
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