To add a "Power Off..." option to the lock screen on Debian 13 with GNOME, you need to modify the GNOME Shell's behavior. By default, the lock screen only shows Unlock and Suspend (or other options like Restart or Shut Down, depending on the system configuration).

Here’s how you can enable the "Power Off..." option on the lock screen without:

• Creating or assuming another user.
• Changing the physical power button behavior.

Method: Edit GNOME Shell Settings via dconf

The lock screen behavior is controlled by GNOME's dconf settings. You can enable the "Power Off..." option by modifying the relevant keys.

Steps:

1. Open a terminal (Ctrl + Alt + T).

2. Check the current lock screen settings: Run the following command to see the current settings for the lock screen:

   bash

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   gsettings get org.gnome.settings-daemon.plugins.power sleep-inactive-ac-timeout
   gsettings get org.gnome.settings-daemon.plugins.power sleep-inactive-battery-timeout

   These commands show the current timeout settings for AC and battery power.

3. Enable the "Power Off..." option: The lock screen's available actions are controlled by the org.gnome.settings-daemon.plugins.power schema. To ensure the "Power Off..." option appears, you need to ensure that the system allows shutdown actions on the lock screen.

   Run the following command to enable the "Power Off..." option:

   bash

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   gsettings set org.gnome.settings-daemon.plugins.power power-button-action 'shutdown'

   This sets the power button action to shutdown, which ensures the "Power Off..." option appears on the lock screen.

4. Verify the changes: Lock your screen (Super + L or manually lock it) and check if the "Power Off..." option appears in the lock screen menu.

Alternative: Use dconf-editor (GUI Method)

If you prefer a graphical approach, you can use the dconf-editor tool to modify the settings.

1. Install dconf-editor (if not already installed):

   bash

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   sudo apt install dconf-editor

2. Open dconf-editor:

   • Navigate to:
     text

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     org > gnome > settings-daemon > plugins > power

   • Look for the power-button-action key and set it to 'shutdown'.

3. Restart GNOME Shell: Press Alt + F2, type r, and press Enter to restart GNOME Shell. This ensures the changes take effect.

4. Check the lock screen: Lock your screen and verify that the "Power Off..." option is now available.

Notes:

• This method does not require creating another user or modifying the physical power button behavior.
• The "Power Off..." option should now appear in the lock screen menu alongside Unlock and Suspend.
• If the option does not appear immediately, try restarting your session or the system.