Is there any way to change what /bin/sh is inside `guix shell [--container]` ?

Is there any way to change what /bin/sh is inside `guix shell [--container]` ?

[Zack Weinberg]

I'm doing experiments with using `guix shell --container` for isolated, reproducible build environments.  I've noticed that no matter how I set up the container, `/bin/sh` points to a full-fat bash, even if the full bash package was not included in the container profile.  For instance

```
guix shell --container bash-minimal coreutils -- sh -c 'ls -l $(command -v sh) /bin/sh'
lrwxrwxrwx 1 zack  users    61 Mar 13 20:07 /bin/sh -> /gnu/store/d99ykvj3axzzidygsmdmzxah4lvxd6hw-bash-5.1.8/bin/sh
lrwxrwxrwx 1 65534 overflow 69 Jan  1  1970 /gnu/store/jc86p6d0i5b3aly5lx5lhb1xa35f2xk8-profile/bin/sh -> /gnu/store/chfwin3a4qp1znnpsjbmydr2jbzk0d6y-bash-minimal-5.1.8/bin/sh

$ guix shell --container busybox -- sh -c 'ls -l $(command -v sh) /bin/sh'
lrwxrwxrwx    1 65534    overflow         7 Jan  1  1970 /gnu/store/96l76flyg617l23c5p32ysjbc72ywjgd-profile/bin/sh -> busybox
lrwxrwxrwx    1 zack       users           61 Mar 13 20:05 /bin/sh -> /gnu/store/d99ykvj3axzzidygsmdmzxah4lvxd6hw-bash-5.1.8/bin/sh
```

Is there any way to change or override this behavior?  What I want is for /bin/sh inside the container to be the same as $GUIX_ENVIRONMENT/bin/sh inside the container.

(If you're about to ask me, "but what if the container profile doesn't include a shell at all?", my response will be "in that case /bin/sh should not exist!"  I can think of several reasons why I might do that on purpose.  Yes, I realize that system(3) won't work in such an environment -- that may in fact be (one of the) goals.)

zw

Re: Is there any way to change what /bin/sh is inside `guix shell [--container]` ?

[Ludovic Courtès]

Hi Zack,

"Zack Weinberg" <zack@owlfolio.org> skribis:

> I'm doing experiments with using `guix shell --container` for isolated, reproducible build environments.  I've noticed that no matter how I set up the container, `/bin/sh` points to a full-fat bash, even if the full bash package was not included in the container profile.

That’s correct.  There’s correctly no way to change that, but we could
definitely add an option to do that.

Would you like to give it a try?  People on IRC and the mailing list can
provide guidance.

Thanks,
Ludo’.

Re: Is there any way to change what /bin/sh is inside `guix shell [--container]` ?

[Zack Weinberg]

On Thu, Mar 16, 2023, at 11:50 AM, Ludovic Courtès wrote:
> "Zack Weinberg" <zack@owlfolio.org> skribis:
>> I'm doing experiments with using `guix shell --container` for
>> isolated, reproducible build environments.  I've noticed that no
>> matter how I set up the container, `/bin/sh` points to a full-fat
>> bash, even if the full bash package was not included in the container
>> profile.
>
> That’s correct.  There’s correctly no way to change that, but we could
> definitely add an option to do that.
>
> Would you like to give it a try?  People on IRC and the mailing list
> can provide guidance.

I don't have a lot of time for side projects at the moment, but if some
time materializes I'll give it a go, sure.  Is there any advice you have
for working on this specific problem, beyond what's in
https://guix.gnu.org/manual/en/html_node/Contributing.html ?

zw