Use editorconfig file

.editorconfig

@@ -0,0 +1,6 @@
+[*.sh]
+indent_style = space
+indent_size = 4
+
+[spec/**]
+ignore = true

.github/workflows/linter.yml

@@ -43,6 +43,7 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           LINTER_RULES_PATH: /
+          EDITORCONFIG_FILE_NAME: .editorconfig
           FILTER_REGEX_EXCLUDE: "requirements/.*"
   check-tox:
     name: Check syntax (tox)

Makefile

@@ -15,13 +15,14 @@ lint:
 	-e RUN_LOCAL=true \
 	-e LINTER_RULES_PATH=/ \
 	-e FILTER_REGEX_EXCLUDE="requirements/.*" \
+	-e EDITORCONFIG_FILE_NAME=.editorconfig \
 	github/super-linter
 	tox -e lint
 
 .PHONY: fmt
 fmt:
-	sudo -E $(DOCKER_CMD) run --rm -u "$$(id -u):$$(id -g)" \
-	-v "$$(pwd):/mnt" -v /mnt/spec -w /mnt mvdan/shfmt -l -w -i 4 -s .
+	command -v shfmt > /dev/null || curl -s "https://i.jpillora.com/mvdan/sh!!?as=shfmt" | bash
+	shfmt -l -w -s .
 	command -v yamlfmt > /dev/null || curl -s "https://i.jpillora.com/google/yamlfmt!!" | bash
 	yamlfmt -dstar **/*.{yaml,yml}
 	command -v prettier > /dev/null || npm install prettier