diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
new file mode 100644
index 0000000..fae1209
--- /dev/null
+++ b/.gitlab-ci.yml
@@ -0,0 +1,16 @@
+# image: scorpil/rust:stable
+
+stages:
+  - test
+
+shellcheck:
+  stage: test
+  image: ubuntu:yakkety
+  before_script:
+    - apt-get update && apt-get install -y shellcheck
+    - locale-gen en_US.UTF-8
+    - export LANG=en_US.UTF-8
+    - export LANGUAGE=en_US:en
+    - export LC_ALL=en_US.UTF-8
+  script:
+    - find . -type f -name '*.sh' -print0 | xargs -n 1 -0 shellcheck --color
diff --git a/V1/led.sh b/V1/led.sh
new file mode 100755
index 0000000..45fade7
--- /dev/null
+++ b/V1/led.sh
@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+# usage: led.sh <port>
+set -o xtrace
+
+# config default
+GPIO_PORT="${1:-18}"
+
+function export_port() {
+  port="${1}"
+  echo "${port}" > /sys/class/gpio/export
+}
+function unexport_port() {
+  port="${1}"
+  echo "${port}" > /sys/class/gpio/unexport
+}
+
+function set_value() {
+  port="${1}"
+  value="${2}"
+  echo "${value}" > "/sys/class/gpio/gpio${port}/value"
+}
+
+function on() {
+  port="${1}"
+  set_value "${port}" "0"
+}
+function off() {
+  port="${1}"
+  set_value "${port}" "1"
+}
+
+# set exit trap
+trap 'unexport_port "${GPIO_PORT}"' EXIT
+
+# init GPIO port
+export_port "${GPIO_PORT}"
+
+# loop led on/off
+while true; do
+  on "${GPIO_PORT}"
+  sleep 1
+  off "${GPIO_PORT}"
+  sleep 1
+done