add shell linter

[teknoraver]

This adds a GitHub action which runs a shell linter on all the .sh files.
ludeeus/action-shellcheck is just an action which relies on
https://github.com/koalaman/shellcheck which is a well known linter.

~/src/libbpf-ci$ find -type f -name '*.sh' |xargs shellcheck -S error
~/src/libbpf-ci$ echo $?
0

[danielocfb]

The code seems fine to me. Thanks!

Would you mind fixing the typo in the subject ("liter") and write a bit more of a commit message? E.g., why did you choose to use ludeeus/action-shellcheck and not any other variant?

Lastly, given that you created a pull request I assume you verified that the check works and reported no issues. Can you please provide a pointer to a sample run as well?

[teknoraver]

oops, my bad, I'll fix the subject

[teknoraver]

Would you mind fixing the typo in the subject ("liter") and write a bit more of a commit message? E.g., why did you choose to use ludeeus/action-shellcheck and not any other variant?

I guess that this is the most used one. Do you suggest another one?

Lastly, given that you created a pull request I assume you verified that the check works and reported no issues. Can you please provide a pointer to a sample run as well?

The check works, but finds tons of warnings.
I'm addressing all of them in my private repo, so to avoid spamming this one.

[danielocfb]

Would you mind fixing the typo in the subject ("liter") and write a bit more of a commit message? E.g., why did you choose to use ludeeus/action-shellcheck and not any other variant?

I guess that this is the most used one. Do you suggest another one?

I am saying that the reasoning is something that most likely should be contained in the commit message, so that in the future somebody can understand why a decision was made.

Lastly, given that you created a pull request I assume you verified that the check works and reported no issues. Can you please provide a pointer to a sample run as well?

The check works, but finds tons of warnings. I'm addressing all of them in my private repo, so to avoid spamming this one.

Either is fine, thanks!

[teknoraver]

This is a sample run of the action on my fork:
https://github.com/teknoraver/libbpf-ci/actions/runs/3329735501/jobs/5507322095

[danielocfb]

Thanks for the update. Few comments.

Disable style suggestions SC1091, SC2181 and SC2001 because they are not
worth fixing in this repository.

Can you please explain what they represent?

[teknoraver]

I refreshed a PR with a smaller one which only fixes the severe errors.
We'll take care of the many warnings later, along with other improvements.

[danielocfb]

Here is a vmtest CI run: https://github.com/kernel-patches/bpf/actions/runs/3339312442
Here libbpf: https://github.com/danielocfb/libbpf/actions/runs/3339319849

[danielocfb]

The pull request causes a new deprecation warning to show up: https://github.com/libbpf/ci/actions/runs/3339058943. We just removed those: kernel-patches/vmtest#142. It's not blocking, but would you mind trying to get the warning removed, @teknoraver ?

[teknoraver]

This needs to be fixed in the action itself:
https://github.com/ludeeus/action-shellcheck/blob/master/action.yaml#L213-L214

This has been already reported to the action author:
ludeeus/action-shellcheck#69

I see that there is a PR already for this, so I hope it will disappear after the merge, as I'm targeting master:
ludeeus/action-shellcheck#70

[teknoraver]

BTW according to GitHub, this deprecation was added last week, and deprecated commands will be available until 31st May 2023:

https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

Let's hope that the action will be fixed in the meantime!

[danielocfb]

CI doesn't seem to have any objections. Neither do I. Thanks!