diff --git a/src/functions.sh b/src/functions.sh
index 4adb615..e8f0429 100644
--- a/src/functions.sh
+++ b/src/functions.sh
@@ -300,6 +300,8 @@ is_debug () {
 }
 
 # Function to check if the script is run in GitHub Actions environment
+# GITHUB_ACTIONS is set when Differential ShellCheck is running in GitHub Actions
+# https://docs.github.com/en/actions/learn-github-actions/variables#default-environment-variables
 is_github_actions () {
   if [[ -z "${GITHUB_ACTIONS}" ]]; then
     return 1
diff --git a/src/index.sh b/src/index.sh
index 7d5db3d..307f4df 100755
--- a/src/index.sh
+++ b/src/index.sh
@@ -5,6 +5,8 @@ CURRENT_DIR="$(dirname "$(readlink -f "$0")")"
 
 # shellcheck source=functions.sh
 . "${SCRIPT_DIR="${CURRENT_DIR}/"}functions.sh"
+# shellcheck source=setup.sh
+. "${SCRIPT_DIR=}setup.sh"
 
 WORK_DIR="${WORK_DIR-../}"
 
diff --git a/src/setup.sh b/src/setup.sh
new file mode 100644
index 0000000..6ce062f
--- /dev/null
+++ b/src/setup.sh
@@ -0,0 +1,12 @@
+# shellcheck shell=bash
+
+# TODO set up required variables
+
+# Set required variables based on the environment
+if is_github_actions; then
+  is_debug && echo "Running in GitHub Actions"
+else
+  is_debug && \
+  echo "Running in non GitHub Actions environment" && \
+  echo "Functionality is limited"
+fi