Get all shell scripts passing shellcheck

[Ericson2314]

Since #10787, we are now running shellcheck on scripts.

Just like with C/C++ formatting, we are excluding almost all existing files by default. However, the reason for doing that is different than for formatting --- fixing shellcheck lint errors does not have the downside of causing merge conflicts churn, but does require manual edits. Thus we're skipping existing files not because it would be potentially bad to get them passing, but because it is more work than is appropriate for a single PR.

Scripts can one-by-one be made passing, which is a great issue to share between new contributors!

[SkamDart]

Is there a way to run individual tests?
I have a bash script that automates away the happy path where we can use shellcheck to auto-apply fixes.
Would be cool to run a n individual tests instead of running the full test suite n times.

#!/usr/bin/env bash

# this file was made by manually editing the list of the shcellcheck exluded files.
#
# Use some vim/emacs magic from the output of
#
# $ cat $_NIX_PRE_COMMIT_HOOKS_CONFIG | yq -y .repos[0].hooks[1].exclude
#
# e.g.
# tests/functional/gc.sh
# tests/functional/add.sh
# tests/functional/fmt.sh
FILES=$(cat /tmp/excluded-files.txt)
MAINT="./maintainers/flake-module.nix"

for file in $FILES
do
    shellcheck -f diff "$file" | git apply
    SC=$?

    # if shellcheck/git patch fails.... manually fix
    if [ $SC -ne 0 ]; then
        echo "$file failed to be formatted manual intervention required"
        nvim $file
    else
        # Remove the processed file from the list
        #
        # we need to escape the nested directories for our regex.
        escaped_file=$(echo "$file" | sed -e 's/[]\/$*.^[]/\\&/g')
        sed -i "/$escaped_file/d" $MAINT

        # Do git stuffs
        git add "$file" "$MAINT"
        git commit -m "housekeeping: shellcheck for $file"
    fi
done

[Ericson2314]

@SkamDart Yes there is! See https://nixos.org/manual/nix/unstable/contributing/testing and ./mk/debug-test.sh tests/functional/${testName}.sh.

[bryanhonof]

What should we do about scripts like the following?

nix/tests/functional/shell.shebang.sh

Lines 1 to 4 in 838b666

	#! @ENV_PROG@ nix-shell
	#! nix-shell -I nixpkgs=shell.nix --no-substitute
	#! nix-shell --pure -i bash -p foo bar
	echo "$(foo) $(bar) $@"

I can't disable SC2230, or at least, I don't think I can.

[Ericson2314]

@bryanhonof we might be able to put some disables in the precommit configuration as a workaround?

[Ericson2314]

Per the discussion in #10857, on issue with shellcheck's --diff is is koalaman/shellcheck#2996, quotes appears in the middle of "words" rather than next to spaces, is a funky style.

In #10857 (comment) I through together this hackjob sed (not fully correct, just a heuristic!) that can help a big fixing.

sed -i -E -e 's/( "[^"]+)"([a-z/=#_1-9-]+)( |\)|$)/\1\2"\3/' tests/functional/**.sh