Fix pacman cache removal in Arch image

[Antiz96]

The --noconfirm pacman flag automatically accepts the default answer for each questions and the default answer to removing cached packages when using pacman -Scc is "N" (no). That means that pacman -Scc --noconfirm does not actually remove cached packages.

Since pacman doesn't have a way to choose to answer yes or no automatically (yet?), a simple workaround is to use yes | pacman -Scc instead. However, while it is recommended to set pipefail when using pipes, it is not possible with the yes command (see this comment for more details).
Although, it should be safe to just use a piped yes without setting pipefail as I don't see how it could be a cause of failure in that particular case.

If using a pipe without setting pipefail is a concern, one can simply run rm -f /var/cache/pacman/pkg/* instead.
I can adapt this PR accordingly if needed.

I remain available if needed :slightly_smiling_face:

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[debarshiray]

@Antiz96 thanks for noticing this!

I wonder if it will be possible to add a test for this. Maybe based on:

$ ls -1 /var/cache/pacman/pkg

In the past, I managed to hack in some tests for the fedora-toolbox images into their Containerfiles. It gives some assurance that future changes to the images or the underlying OS won't regress anything.

[Antiz96]

@debarshiray You're welcome :)

Could add a line like this for instance:

RUN [ -z "$(ls /var/cache/pacman/pkg)" ] || echo "non empty" # or exit, or whatever is needed

Although, to be honest, I'm not so worried about yes | pacman -Scc failing to clean the cache, but you can never be too careful I guess :smile:
I can open another PR for the above test if you want to.

[debarshiray]

@debarshiray You're welcome :)

Could add a line like this for instance:

RUN [ -z "$(ls /var/cache/pacman/pkg)" ] || echo "non empty" # or exit, or whatever is needed

Sounds good to me.

Although, to be honest, I'm not so worried about yes | pacman -Scc failing to clean the cache, but you can never be too careful I guess 😄 I can open another PR for the above test if you want to.

Ultimately @Foxboron is the maintainer of the Arch Linux images. So, I leave it to him.

I personally tend to err on the side of caution. Someone might casually change something without checking, and then who knows? After all, you did discover this problem where the existing attempt wasn't working as expected. :)