Apa itu Shell Script?

Shell script adalah file berisi kumpulan command yang dieksekusi secara berurutan. Berguna untuk mengotomasi tugas repetitif seperti deployment, backup, atau setup environment.

Dasar Shell Script

#!/bin/bash
# Shebang line: menentukan interpreter

# Variabel (tanpa spasi di sekitar =)
APP_NAME="my-app"
PORT=3000
echo "Starting $APP_NAME on port $PORT"

# Input dari user
read -p "Enter environment: " ENV
echo "Deploying to $ENV"

Conditional & Loop

# If-else
if [ -f ".env" ]; then
    echo ".env file exists"
elif [ -f ".env.example" ]; then
    cp .env.example .env
    echo "Created .env from example"
else
    echo "No .env file found!"
    exit 1
fi

# Loop
for file in *.log; do
    echo "Processing: $file"
    gzip "$file"
done

# While loop
while ! curl -s http://localhost:3000/health > /dev/null; do
    echo "Waiting for app to start..."
    sleep 2
done
echo "App is ready!"

Contoh: Deploy Script

#!/bin/bash
set -e  # stop jika ada error

APP_DIR="/var/www/my-app"
BRANCH="${1:-main}"  # default ke main

echo "=== Deploying branch: $BRANCH ==="

cd "$APP_DIR"
git fetch origin
git checkout "$BRANCH"
git pull origin "$BRANCH"

# Install dependencies
npm ci --production
php artisan migrate --force

# Restart services
sudo systemctl restart php-fpm
sudo systemctl restart nginx

echo "=== Deploy complete! ==="

Best Practices

• Selalu gunakan set -e agar script berhenti saat error
• Quote variabel: "$VAR" bukan $VAR
• Gunakan ${VAR:-default} untuk default value
• Tambahkan echo untuk progress feedback