where should i put systemd .ser…

On Debian, you should place custom systemd service files in:

## **`/etc/systemd/system/`**

This is the recommended location for:
- Custom service files you create
- Local modifications to existing services
- Third-party service files

## Example:
```bash
sudo nano /etc/systemd/system/myapp.service
```

## After creating the service file:

1. **Reload systemd** to recognize the new service:
   ```bash
   sudo systemctl daemon-reload
   ```

2. **Enable the service** (if you want it to start at boot):
   ```bash
   sudo systemctl enable myapp.service
   ```

3. **Start the service**:
   ```bash
   sudo systemctl start myapp.service
   ```

## Other systemd directories (for reference):

- **`/lib/systemd/system/`** - System-provided service files (don't modify these directly)
- **`/usr/lib/systemd/system/`** - Package-provided service files
- **`/run/systemd/system/`** - Runtime service files (temporary)
- **`~/.config/systemd/user/`** - User-specific service files (for `systemctl --user`)

## Priority order:
Files in `/etc/systemd/system/` take precedence over those in `/lib/systemd/system/`, so you can override system defaults by placing files with the same name in `/etc/systemd/system/`.