Set permissions for a directory like /var/www or /etc/nginx

set-permissions.sh

#!/bin/bash

set -e

print_usage() {
    echo ""
    echo "Usage: $0 /path/to/directory [group]"
    echo ""
    echo "Arguments:"
    echo "  /path/to/directory   Target directory to apply permissions"
    echo "  group                Optional group name (default: users)"
    echo ""
    echo "This script:"
    echo "  - Keeps the current owner (user)"
    echo "  - Changes the group to the one you specify (default: users)"
    echo "  - Sets directory permissions to 775 with g+s (so new files inherit group)"
    echo "  - Sets file permissions to 664"
    echo ""
    echo "Example:"
    echo "  $0 /etc/nginx"
    echo "  $0 /home/kalio/project devteam"
    echo ""
}

# --- Argument Parsing ---
if [[ "$1" == "-h" || "$1" == "--help" ]]; then
    print_usage
    exit 0
fi

TARGET_DIR="$1"
GROUP="${2:-users}"

if [[ -z "$TARGET_DIR" ]]; then
    echo "❌ Error: Target directory is required."
    print_usage
    exit 1
fi

if [[ ! -d "$TARGET_DIR" ]]; then
    echo "❌ Error: '$TARGET_DIR' is not a valid directory."
    exit 1
fi

if ! getent group "$GROUP" > /dev/null; then
    echo "❌ Error: Group '$GROUP' does not exist. Create it with: sudo groupadd $GROUP"
    exit 1
fi

OWNER=$(stat -c "%U" "$TARGET_DIR")

echo "🔧 Applying permissions to: $TARGET_DIR"
echo "👤 Owner will remain: $OWNER"
echo "👥 Group will be set to: $GROUP"
echo ""

# --- Apply Permissions ---
echo "→ Setting ownership recursively to $OWNER:$GROUP ..."
sudo chown -R "$OWNER:$GROUP" "$TARGET_DIR"

echo "→ Setting directory permissions to 775 and adding setgid bit ..."
sudo find "$TARGET_DIR" -type d -exec chmod 2775 {} \;

echo "→ Setting file permissions to 664 ..."
sudo find "$TARGET_DIR" -type f -exec chmod 664 {} \;

echo ""
echo "✅ Done: Collaborative permissions applied successfully!"