Add shellcheck

.github/workflows/shellcheck.yml

@@ -0,0 +1,22 @@
+name: shellcheck
+on: [push, pull_request]
+
+jobs:
+  shellcheck:
+    name: Shell Check
+    runs-on: ubuntu-latest
+    container:
+      image: opensuse/leap:15.3
+    steps:
+      - uses: actions/checkout@v1.2.0
+      - name: Update packages
+        run: zypper --non-interactive --gpg-auto-import-keys ref
+      - name: Install openSUSE dependencies
+        run: zypper --non-interactive --gpg-auto-import-keys install ShellCheck
+
+      - name: shellcheck
+        run: |
+          set -x
+          for i in $(find . -type f -name '*.sh'); do
+            shellcheck -s bash --exclude=SC2181 --exclude=SC1090 --exclude=SC2006 --exclude=SC2086 $i
+          done

README.md

@@ -1,5 +1,5 @@
-:shell: Unix Shell Scripts
-================================
+:shell: Unix Shell Scripts [![Build Status](https://github.com/jonaski/shellscripts/workflows/shellcheck/badge.svg)](https://github.com/jonaski/shellscripts/actions)
+==========================
 
 These are some of the various unix shell scripts I've made over the years.