linters: Add shellcheck

Add shellcheck linter both as an action and as a Makefile rule.
Fail on severity greater than 'warning' to avoid refactoring current
scripts.

Signed-off-by: Alex Apostolescu <[email protected]>

Author: Alex-deVis

.github/workflows/actions.yml

@@ -108,3 +108,25 @@ jobs:
         with:
           options: "--check --diff"
           src: ${{ env.FILES }}
+
+  shellcheck:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Get changed shell files
+        uses: tj-actions/changed-files@v45
+        id: changed-files
+        with:
+          files: "**/*.{sh,bash}"
+          separator: " "
+
+      - name: shellcheck
+        uses: ludeeus/[email protected]
+        with:
+          version: v0.10.0
+          severity: warning
+          ignore_paths: "."                                                       # Ignore all files
+          additional_files: ${{ steps.changed-files.outputs.all_changed_files }}  # Only check changed files

Makefile

@@ -40,8 +40,8 @@ clean: stop_bash
 cleanall: clean
 	-docker inspect --type=image $(IMAGE_NAME) > /dev/null 2>&1 && docker image rm $(IMAGE_NAME)
 
-.PHONY: lint markdownlint cpplint black
-lint: markdownlint cpplint black
+.PHONY: lint markdownlint cpplint black shellcheck
+lint: markdownlint cpplint black shellcheck
 
 CHANGED_MD_FILES = $(call get_changed_files,\.md$$)
 markdownlint:
@@ -68,6 +68,14 @@ black:
 			black --check --diff $(CHANGED_PY_FILES); \
 	fi
 
+CHANGED_SHELL_FILES = $(call get_changed_files,\.\(sh\|bash\)$$)
+shellcheck:
+	@echo "Checking shell scripts ..."
+	@if [ "$(CHANGED_SHELL_FILES)" ]; then \
+		docker run --rm -v $(PWD):/data --workdir=/data koalaman/shellcheck-alpine:v0.10.0 \
+			shellcheck --severity=warning $(CHANGED_SHELL_FILES); \
+	fi
+
 # Get a list of files that changed in the current branch and match the given pattern
 define get_changed_files # $(1): pattern
 $(shell git diff --name-only HEAD $(shell git merge-base HEAD main) | grep "$(1)" | tr '\n' ' ')