Use shellcheck to improve the code quality

.github/workflows/main.yml

@@ -0,0 +1,30 @@
+# This is a basic workflow to help you get started with Actions
+
+name: CI
+
+# Controls when the workflow will run
+on:
+  # Triggers the workflow on push or pull request events but only for the main branch
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+# A workflow run is made up of one or more jobs that can run sequentially or in parallel
+jobs:
+  # This workflow contains a single job called "build"
+  build:
+    # The type of runner that the job will run on
+    runs-on: ubuntu-latest
+
+    # Steps represent a sequence of tasks that will be executed as part of the job
+    steps:
+      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
+      - uses: actions/checkout@v2
+
+      # Runs a single command using the runners shell
+      - name: shell check
+        run: docker-compose run --rm shellcheck ./validate.sh

docker-compose.yaml

@@ -0,0 +1,8 @@
+---
+version: '3.9'
+services:
+  shellcheck:
+    image: koalaman/shellcheck-alpine:latest
+    volumes:
+      - ".:/build"
+    working_dir: /build

entrypoint.sh

@@ -1,10 +1,10 @@
-#!/bin/sh -l
+#!/bin/sh
+# shellcheck disable=SC3060
 
 set -e  # if a command fails it stops the execution
 set -u  # script fails if trying to access to an undefined variable
 
 echo "[+] Action start"
-SOURCE_BEFORE_DIRECTORY="${1}"
 SOURCE_DIRECTORY="${2}"
 DESTINATION_GITHUB_USERNAME="${3}"
 DESTINATION_REPOSITORY_NAME="${4}"

validate.sh

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+#!/bin/sh
+# shellcheck disable=SC2044
+
+set -eu pipefile
+
+rc=0
+for filename in $(find ./* -name '*.sh'); do
+  echo "Start to validating ${filename}"
+  shellcheck "${filename}" || exit $?
+  echo "🚀Successfully Validated ${filename}"
+done
+
+exit $rc