Add shell script linter

Author: saliceti

scripts/docker/docker.lib.sh

@@ -49,7 +49,7 @@ function docker-build() {
 
   # Tag the image with all the stated versions, see the documentation for more details
   for version in $(_get-all-effective-versions) latest; do
-    if [ ! -z "$version" ]; then
+    if [ -n "$version" ]; then
       docker tag "${tag}" "${DOCKER_IMAGE}:${version}"
     fi
   done
@@ -312,7 +312,7 @@ function _get-effective-tag() {
 
   local tag=$DOCKER_IMAGE
   version=$(_get-effective-version)
-  if [ ! -z "$version" ]; then
+  if [ -n "$version" ]; then
     tag="${tag}:${version}"
   fi
   echo "$tag"

scripts/shared.mk

@@ -59,8 +59,13 @@ HELP_SCRIPT = \
 		} \
 	}
 
+shellscript-lint-all: # Lint all shell scripts in the scripts directory, do not fail on error, just print the error messages @Quality
+	for file in $$(find scripts -type f -name "*.sh"); do \
+		file=$${file} scripts/shellscript-linter.sh ||: ; \
+	done
+
 .PHONY: _install-tool _install-tools
 .ONESHELL:
 MAKEFLAGS := --no-print-directory
 SHELL := /bin/bash
-SHELLFLAGS := -cex
+SHELLFLAGS := -cex