scripts: Add ShellCheck lint target

Add a tracked runner that discovers Bash scripts under scripts/ and
checks them with external source resolution enabled. Expose it through
the top-level Makefile.

Run the same entry point from the patch lint workflow whenever a range
touches Bash lint inputs, and report its result explicitly.

.agents/skills/lint-patch/SKILL.md

@@ -38,9 +38,14 @@ Run at least these components:
 2. Run `./scripts/checkpatch_commits "$base"`. This is the tracked SCST
    entry point for every commit in `base..HEAD`; the preflight makes
    `HEAD == head`. Do not invent options or use an untracked helper.
-3. Manually verify Linux kernel coding style for every changed kernel C and
+3. If the range changes a tracked Bash script in `scripts/`,
+   `scripts/run-shellcheck` itself, or the `shellcheck` target in the
+   top-level `Makefile`, run `./scripts/run-shellcheck` from the repository
+   root. A missing `shellcheck` is `BLOCKED` in that case; report
+   `NOT_APPLICABLE` for other ranges.
+4. Manually verify Linux kernel coding style for every changed kernel C and
    header file. Use the diff plus enough surrounding code to judge context.
-4. Inspect every commit as an independently reviewable semantic unit. Check
+5. Inspect every commit as an independently reviewable semantic unit. Check
    its subject and body against applicable repository rules and current SCST
    history, including concise imperative wording and established prefixes.
 
@@ -79,6 +84,7 @@ End with exactly one marker block:
 LINT_EXECUTOR: main
 DIFF_CHECK: <PASS|FAIL|BLOCKED>
 CHECKPATCH: <PASS|WAIVED|FAIL|NOT_APPLICABLE|BLOCKED>
+SHELLCHECK: <PASS|FAIL|NOT_APPLICABLE|BLOCKED>
 CODE_STYLE: <PASS|FAIL|NOT_APPLICABLE|BLOCKED>
 COMMIT_STYLE: <PASS|FAIL|BLOCKED>
 LINT_BASELINE: <CLEAN|PRESENT|BLOCKED>

Makefile

@@ -102,6 +102,7 @@ SCST_SOURCE_FILES = $(shell if [ -e scripts/list-source-files ]; then	\
 help:
 	@echo "		tags                  : make tags"
 	@echo "		cov-build             : make coverity build"
+	@echo "		shellcheck            : check Bash scripts"
 	@echo ""
 	@echo "		all                   : make all"
 	@echo "		clean                 : clean files"
@@ -194,6 +195,9 @@ cov-build:
 			exit $$?;					   \
 	done
 
+shellcheck:
+	scripts/run-shellcheck
+
 all clean extraclean install uninstall:
 	if [ $@ = extraclean ]; then rm -f TAGS tags cscope.out; fi
 	for d in $(SCST_DIR) $(ISCSI_DIR) $(QLA_DIR) $(SRP_DIR)	     \
@@ -513,7 +517,7 @@ multiple-release-archives:
 2debug:
 	cd $(SCST_DIR) && $(MAKE) $@
 
-.PHONY: help tags cov-build all clean extraclean install uninstall \
+.PHONY: help tags cov-build shellcheck all clean extraclean install uninstall \
 	scst scst_clean scst_extraclean scst_install scst_uninstall \
 	docs docs_clean docs_extraclean \
 	scstadm scstadm_clean scstadm_extraclean scstadm_install scstadm_uninstall \

scripts/run-shellcheck

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+set -euo pipefail
+
+script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+
+if ! command -v shellcheck >/dev/null 2>&1; then
+  echo "Error: shellcheck has not been installed." >&2
+  exit 1
+fi
+
+source_files="$("$script_dir/list-source-files" "$script_dir")"
+
+cd "$script_dir"
+
+bash_scripts=()
+while IFS= read -r file; do
+  [ -n "$file" ] || continue
+  IFS= read -r first_line < "$file" || first_line=
+  case "$first_line" in
+    '#!'*bash*) bash_scripts+=("$file");;
+  esac
+done <<<"$source_files"
+
+if [ "${#bash_scripts[@]}" -eq 0 ]; then
+  echo "Error: no Bash scripts found under scripts/." >&2
+  exit 1
+fi
+
+shellcheck -x -P SCRIPTDIR "${bash_scripts[@]}"