Make shellcheck more efficient

Only checking changed files

.githooks/pre-commit/01-shellcheck.sh

@@ -2,15 +2,18 @@
 
 set -euo pipefail
 
-DIR="$(pwd)" # hooks are always ran from the root of the repo
+# hooks are always ran from the root of the repo
 
-submodule_dirs=$(git submodule | awk '{ printf "-not -path '"$DIR"'/" $2 "/* " }')
-set -f # disable globbing
+# get all files that have been changed
+all_diff_files=`git diff --name-only --cached --ignore-submodules=all --diff-filter=ACM`
+if [ -z "$all_diff_files" ]; then exit 0; fi
+diff_files=`echo "$all_diff_files" | grep -v /.testsupport/`
 # shellcheck disable=SC2086
-sh_files=$(find "$DIR" \( -name '*.sh' -or -name '*.bash' \) -not -path "$DIR"/.testsupport/'*' $submodule_dirs)
+exec_files=$(find $diff_files -exec sh -c 'head -n1 $1 | grep -qE '"'"'^#!(.*/|\/usr\/bin\/env +)bash'"'" sh {} \; -exec echo {} \;)
 # shellcheck disable=SC2086
-exec_files=$(find "$DIR" -not -path "$DIR"/.testsupport/'*' $submodule_dirs -type f -exec sh -c 'head -n1 $1 | grep -qE '"'"'^#!(.*/|\/usr\/bin\/env +)bash'"'" sh {} \; -exec echo {} \;)
-set +f
+sh_files=$(find $diff_files \( -name '*.sh' -or -name '*.bash' \))
 all_files=`echo -e "$sh_files\n$exec_files" | sort | uniq`
+echo "Running shellcheck on the following files:"
+echo "$all_files"
 # shellcheck disable=SC2086
 shellcheck --shell bash $all_files