Retrieving UID and GID on Synology NAS¶

Introduction¶

Synology NAS devices run on a Linux-based operating system, which manages file and user permissions using User IDs (UIDs) and Group IDs (GIDs). Knowing these IDs is essential when configuring permissions for network shares, Docker containers, or custom scripts. This guide covers two methods to retrieve UID and GID on a Synology NAS: via SSH (command-line interface) and through a custom script on the Synology DSM web interface.

Enabling SSH Access¶

Before using the CLI method, SSH must be enabled on your Synology NAS:

1. Log in to DSM (DiskStation Manager) via your web browser.
2. Navigate to Control Panel → Terminal & SNMP.
3. Check the box Enable SSH service and click Apply.
4. Note your NAS IP address (found under Control Panel → Network).

Method 1: Using SSH and the id Command¶

Once SSH is enabled, follow these steps to retrieve your UID and GID:

1. Open a terminal (Linux/macOS, Windows) or tools like PuTTY, Termius as example.
2. Connect to your Synology NAS using SSH:

   ssh username@your-nas-ip
   

3. Enter your password when prompted.
4. Run the id command to display UID and GID:

   id
   

uid=1026(user) gid=100(users) groups=100(users), 101(administrators)

• uid=1026 → The UID of the logged-in user.
• gid=100 → The primary group ID.
• Additional groups indicate membership in multiple groups.

To check another user’s UID and GID, use:

id <username>

Method 2: Using a Custom Script in DSM Web (E-Mail)¶

For users who prefer a web-based solution, a simple script can be executed via Synology’s Task Scheduler:

Creating the Script¶

1. Log in to DSM.
2. Open Control Panel → Task Scheduler.
3. Click Create → User-defined script.
4. Under General, name the task (e.g., "Retrieve_UID_GID").
5. Set User to the account whose UID and GID you want to retrieve.
6. Go to the Task Settings tab and enter the following script:

    id
   

7. Click OK and then Run the task.
8. An email containing your UID and GID information will be sent to you.

Method 3: Using a Custom Script in DSM Web (Shared Folder)¶

For users who prefer a web-based solution, a simple script can be executed via Synology’s Task Scheduler:

Creating the Script¶

1. Log in to DSM.
2. Open Control Panel → Task Scheduler.
3. Click Create → User-defined script.
4. Under General, name the task (e.g., "Retrieve_UID_GID").
5. Set User to the account whose UID and GID you want to retrieve. This user must also have the necessary permissions to write to the specified shared folder.
6. Go to the Task Settings tab and enter the following script:

   echo "Current User ID (UID): $(id -u)" > /volume1/<Shared Folder>/UID_GID_Info.txt
   echo "Current Group ID (GID): $(id -g)" >> /volume1/<Shared Folder>/UID_GID_Info.txt
   

7. Click OK and then Run the task.
8. Navigate to /volume1/<Shared Folder>/UID_GID_Info.txt using File Station or SSH to view the results.

Conclusion¶

Whether using SSH or a custom DSM script, retrieving UID and GID on a Synology NAS is straightforward. The command-line method provides instant results, while the script-based approach is useful for users who prefer a graphical interface. Understanding UID and GID is essential for advanced permission management and integration with other services like Docker, NFS, and SMB permissions.