qubes-doc/user/advanced-topics/disposable-customization.rst

========================
Disposable customization
========================

.. warning::

      This page is intended for advanced users.

Introduction
------------


A :doc:`disposable </user/how-to-guides/how-to-use-disposables>` can be based on any :term:`disposable template`. You can have as many disposables or disposable templates as you'd like. This page contains information on advanced methods to use disposables, how to customize them, how to deal with multiple disposable templates and how to delete them.


Security
--------


If a disposable template becomes compromised, then any disposable based on that disposable template could be compromised. Therefore, you should not make any risky customization (e.g., installing untrusted browser plugins) in important disposable templates. In particular, the *default* disposable template is important because it is used by most app qubes. This means that a compromised disposable template, could be used to derive disposables that will have access to everything that you choose to open in a disposable. For this reason, it is strongly recommended that you base the default disposable template on a trusted template and refrain from making any risky customization to it.

Disposables and local forensics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


At this time, disposables should not be relied upon to circumvent local forensics, as they `do not run entirely in RAM <https://groups.google.com/d/topic/qubes-devel/QwL5PjqPs-4/discussion>`__. When it is essential to avoid leaving any trace, consider using `Tails <https://tails.net>`__ on bare-metal, as using Tails on a `qube cannot be relied on for amnesiac purposes <https://tails.net/doc/advanced_topics/virtualization/index.en.html#index2h1>`__.

Disposables settings inheritance
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


Similarly to how app qubes are based on their underlying :term:`template`, disposables are based on their underlying :term:`disposable template`.

By default, a disposable will inherit the network and firewall settings of the disposable template on which it is based. Therefore, launching a disposable from an app qube will result in it using the network/firewall settings of the disposable template on which it is based. For example, if an app qube uses ``sys-net`` as its net qube, but the default system disposable uses ``sys-whonix``, any disposable launched from this app qube will have ``sys-whonix`` as its net qube.

.. warning:: Changing the net qube setting for the system's default disposable template *does* affect the net qube of its new disposables. Different disposable templates with individual net qube settings can be added to the app menu.

You can even set an app qube that has also been configured as a disposable template to use itself, so disposables launched from within the app qube/disposable template would inherit the same settings. This is recommended to avoid sharing too much information about your system, as inhering the same configuration means it helps prevent network leaks. For example, ``anon-whonix`` has its ``default_dispvm`` a Whonix-Workstation qube such as :samp:`whonix-workstation-{12}-dvm` (where :samp:`{12}` is the template's release number), instead of the system default. This ensures that all traffic goes through the intended network chain.

.. warning:: The opposite is also true. If you have changed ``anon-whonix``'s ``default_dispvm`` to use the system default, and the system default disposable template uses ``sys-net``, launching a disposable from inside ``anon-whonix`` will result in the disposable using ``sys-net``.

Advanced disposable's usage
---------------------------


Open an program in a disposable via command line (from app qube)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


Sometimes it can be useful to start an arbitrary program in a disposable. This can be done from an app qube with :program:`qvm-run-vm`:

.. code:: console

      [user@work ~]$ qvm-run-vm -- '@dispvm' qubes-run-terminal

The ``work`` qube default disposable template derives a disposable to execute the program.

Open a link in a disposable based on a non-default disposable template via command line (from app qube)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


Suppose that you have a qube named ``email`` and its default disposable template ``email-dvm`` has no networking (e.g., so that untrusted attachments can't phone home). However, sometimes you want to open email links in disposables. Obviously, you can't use the default disposable template, since it has no networking, so you need to be able to specify a different disposable template, such as ``net-dvm``

Open the :doc:`user policy </user/how-to-guides/how-to-edit-a-policy>` and insert the following rule:

.. code:: text

      # SERVICE      ARGUMENT  FROM   TO               ACTION
      qubes.OpenURL  *         email  @dispvm:net-dvm  allow

The line above means:

- SERVICE: ``Open URL`` request from ``Qubes`` vendor.

- ARGUMENT: Any argument is allowed.

- FROM: ``email`` qube.

- TO: A disposable based on the disposable template ``net-dvm``.

- ACTION: Allow action to proceed.

In other words, the ``email`` qube will be allowed to create a new disposable based on ``net-dvm`` and open a URL inside of that disposable. For more information about Qrexec usage, checkout :ref:`the policy directives <developer/services/qrexec:specifying vms: tags, types, targets, etc.>`.

To check if everything is working as expected, from the ``email`` qube with :program:`qvm-open-in-vm`:

.. code:: console

      [user@email ~] $ qvm-open-in-vm -- '@dispvm:net-dvm' 'https://www.qubes-os.org'

The ``email`` qube requests to open an URL in a non default disposable template ``net-dvm``, which will derive a disposable and navigate to the link.

Make a particular application open everything in a disposable
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


You can enable a :ref:`qube service <user/how-to-guides/how-to-enable-a-service:how to enable a qube service>` to cause an application in a qube to open files and URLs in a disposable. In order to accomplish this, enable a service named :samp:`app-dispvm.{X}` in that qube, where :samp:`{X}` is the application ID, which is the application name minus the :file:`.desktop` extension.

For instance, to have Mozilla Thunderbird application open all attachments in a disposable, find its application name with |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> TEMPLATES --> <DISPOSABLE_TEMPLATE> --> Settings --> Applications`, hover your mouse over the application to see the ``.desktop filename``. Or use the command line equivalent:

.. code:: console

      qvm-appmenus --get-available --i-understand-format-is-unstable <QUBE> | grep -i thunderbird

In the current case, we identified the application ID to be ``net.thunderbird.Thunderbird`` (in your case it may as well be ``thunderbird``). Finally, enable the ``app-dispvm.net.thunderbird.Thunderbird`` service via the :ref:`qube settings <user/how-to-guides/how-to-enable-a-service:how to enable a service in the settings>`.

.. warning:: This feature is currently somewhat experimental, and only works for Linux qubes. It is known to work with Thunderbird and Wire, but it may fail to work with some applications that do not honor all XDG environment variables. If the feature does not work for you, please file a bug report.

Open a particular file type in a disposable
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


You can set :file:`qvm-open-in-dvm.desktop` as the handler for a given MIME type (such as :mimetype:`application/pdf`). This will cause all files of that type to open in a disposable. This works in disposable templates too, but be careful: if your disposable template is set to use :file:`qvm-open-in-dvm.desktop` to open a certain kind of file, every disposable based on it will be as well.

.. warning:: If the disposable template is its own default disposable template (as is often the case), this will result in a loop: :program:`qvm-open-in-dvm` will attempt to execute :program:`qubes.OpenURL` in a new disposable, but that will in turn execute :program:`qvm-open-in-dvm`. A question dialog will appear to confirm if this is the intended behavior or not.

This will *not* override the internal handling of PDF documents in Web browsers. This is typically okay, though, in-browser PDF viewers have a fairly good security record, especially when compared to non-browser PDF viewers. In particular, the attack surface of PDF viewing in Firefox is usually less than that of viewing an ordinary Web page.

Set the default disposable template
-----------------------------------


Set the system's default disposable template
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


The system's default disposable template can be configured in |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> Settings (icon) --> Qubes Tools --> Qubes Global Config --> General --> Default disposable template`, choose to your liking and click :guilabel:`Apply Changes and Close`.

.. image:: /attachment/doc/r4.3-disp-default-global.png
   :alt: Global config window with system's default disposable template item emphasized.


This can also be changed from the command line with with :program:`qubes-prefs`:

.. code:: console

      user@dom0:~$ qubes-prefs default_dispvm <DISPOSABLE_TEMPLATE>

The above setting is used whenever a qube has the property ``default_dispvm`` set to default, request starting a new disposable and do not specify which one, for example, via file manager context menu :guilabel:`Edit/View in disposable qube` or :program:`qvm-open-in-dvm` tool), also with :guilabel:`Convert in disposable qube` (:program:`qvm-convert-img`, :program:`qvm-convert-pdf`).

Set the qube's default disposable template
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


The per qube default disposable template can be configured in the app menu, for example, to change the setting for the ``work`` qube, in |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> APPS --> work --> Settings --> Advanced --> Default disposable template`, select your preference and click :guilabel:`&OK` to apply the changes and close the window.

.. image:: /attachment/doc/r4.3-disp-default-local.png
   :alt: Qube settings of ``work`` with qube's default disposable template item emphasized.

This can also be changed from the command line with :program:`qvm-prefs`:

.. code:: console

      user@dom0:~$ qvm-prefs work default_dispvm <DISPOSABLE_TEMPLATE>

A qube can be allowed to use :ref:`multiple disposable templates <user/advanced-topics/disposable-customization:open a link in a disposable based on a non-default disposable template via command line (from app qube)>` if you choose so and have configured the :ref:`policy to allow <developer/services/qrexec:specifying vms: tags, types, targets, etc.>`.

Customize a disposable
----------------------


.. warning:: If you are trying to customize Tor Browser in a Whonix disposable, please consult the `Whonix documentation <https://www.whonix.org/wiki/Tor_Browser/Advanced_Users#disposable_Template_Customization>`__ instead.

Change qube settings
^^^^^^^^^^^^^^^^^^^^


It is possible to change the disposable settings just like any other qube. You might, for example, want to disable all networking for the specific disposable template by default, which can be done by setting the net qube to ``none``. Then, whenever you start a new disposable, you can choose your desired net qube manually by changing the newly-started disposable's settings.

Add programs to the app menu
^^^^^^^^^^^^^^^^^^^^^^^^^^^^


For added convenience, arbitrary programs can be added to the app menu of the disposable template :ref:`just like for any other qube <user/troubleshooting/app-menu-shortcut-troubleshooting:How-to add a shortcut>`.

In order to do that, go to |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> TEMPLATES --> <DISPOSABLE_TEMPLATE> --> Settings --> Applications` and select desired applications as for any other qube.

Only applications whose :ref:`main process keeps running until you close the application <user/how-to-guides/how-to-use-disposables:call to the application succeeds but disposable exits too soon>` will work.

Change application settings manually
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


It is also possible to change application settings of a disposable by customizing the disposable template:

1. Start a terminal (or your chosen application) in the :samp:`{<DISPOSABLE_TEMPLATE>}` qube with |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> TEMPLATES --> <DISPOSABLE_TEMPLATE> --> Run Terminal` or by running the following command in a :term:`GUI domain`:

   .. code:: console

         user@dom0:~$ qvm-run --service -- <DISPOSABLE_TEMPLATE> qubes.StartApp+qubes-run-terminal

2. Change the applications settings, as desired. Some examples of changes you may want to make include:

   - Firefox's default startup settings and homepage.

   - Default editor, image viewer. In Debian derivatives, this can be done with the :program:`mimeopen` command.

3. Shutdown the qube, either with Qubes Domains widget, |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> TEMPLATES --> <DISPOSABLE_TEMPLATE> --> Shutdown`, :program:`qvm-shutdown` from the :term:`GUI domain` terminal or with :program:`poweroff` from qube's terminal.

Change application settings dynamically
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


It is possible to specify data from the :term:`GUI domain` to be read inside the qube using :doc:`vm-config.* features <core-admin-client:manpages/qvm-features>`. This is useful to pass secrets to a single qube instead of writing to the disposable template, which would be shared with all descendants of it.

Let's take for example ``sys-net``, which could be a disposable if you enabled that option during installation. In that case, it's template is ``default-dvm``, but that is also the template of unnamed disposables that launch applications which you don't trust. It would be improper to write the Wi-Fi password to ``default-dvm``, as it would expose it to numerous qubes. Instead, write the data as a qube feature using the :samp:`vm-config.{X}` syntax, where :samp:`{X}` is any valid identification string you'd like.

.. note:: It is up to each qube to handle these entries. In this case, :program:`nmcli` command should be called from somewhere during qube startup to configure the network, it is up to the user to manage it.

From the :term:`GUI domain`:

.. code:: console

      user@dom0:~$ qvm-features sys-net vm-config.wifi-ssid <SSID>
      user@dom0:~$ qvm-features sys-net vm-config.wifi-pass <PASSWORD>

From the configured qube, ``sys-net``:

.. code:: console

      [user@sys-net ~] $ qubesdb-read /vm-config/wifi-ssid
      [user@sys-net ~] $ qubesdb-read /vm-config/wifi-pass

Create a new disposable template
--------------------------------


You can create as many disposable templates as you want. First, you need to :ref:`create an app qube <introduction/getting-started:adding, removing, and listing qubes>`.

Next, go to |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> APPS --> <DISPOSABLE_TEMPLATE> --> Settings --> Advanced --> Disposable template` and enable it, at last, click on :guilabel:`&OK` to accept the changes and close the window. To modify settings of the disposable template itself or how programs are run on it, use the :guilabel:`TEMPLATES` tab.

You can also use the command line equivalent:

.. code:: console

      user@dom0:~$ qvm-create --template <TEMPLATE> --label red <DISPOSABLE_TEMPLATE>
      user@dom0:~$ qvm-prefs <DISPOSABLE_TEMPLATE> template_for_dispvms True
      user@dom0:~$ qvm-features <DISPOSABLE_TEMPLATE> appmenus-dispvm 1

The ``appmenus-dispvm`` feature is only necessary if you intend to launch unnamed disposables derived from this disposable template via graphical applications. When enabled, new entries will be available for each application in |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> APPS --> <DISPOSABLE_TEMPLATE> --> <APPLICATION> --> New disposable qube from <DISPOSABLE_TEMPLATE>` while disposable qube desktop entries will have ``(dvm)`` string inserted. Clicking on this entry will launch the application in a new unnamed disposable based on the disposable template (not in the disposable template itself).

.. important:: Application shortcuts that existed before setting this feature will not be updated automatically. Please go to |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> APPS --> <DISPOSABLE_TEMPLATE> --> Settings`, in the :guilabel:`Applications` tab, unselect all existing shortcuts by clicking :guilabel:`<<`, then click :guilabel:`&OK` and close the dialog. Give it a few seconds and then reopen and re-select all the shortcuts you want to see in the menu. See :doc:`app menu shortcut troubleshooting </user/troubleshooting/app-menu-shortcut-troubleshooting>` for background information.

Creating named disposables for service qubes
--------------------------------------------


You can use a :term:`named disposable` for a :term:`service qube` (such as those with the ``sys-*`` naming scheme) as long as they are stateless. For example, a ``sys-net`` using DHCP or ``sys-usb`` will work. In most cases ``sys-firewall`` will also work, even if you have configured app qube firewall rules. The only exception is if you require something like qube to qube communication and have manually edited :program:`nftables` or other items directly inside the firewall app qube.

Named disposable for service qubes without PCI devices via GUI
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


To create one that has no PCI devices attached, such as for ``sys-firewall``, create a :ref:`named disposable <user/how-to-guides/how-to-use-disposables:how to create named disposables>`. Write a name, choose a label and select :guilabel:`Launch Qube Settings after creation`. Click :guilabel:`Create new qube` to complete creation. When the :guilabel:`Qube Settings` opens:

- :menuselection:`Basic --> Start qube automatically on boot`
- :menuselection:`Basic --> Net qube --> sys-net`
- :menuselection:`Advanced --> Provides network`

Click :guilabel:`&OK` to save changes and close the window.

On the :term:`GUI domain` terminal, disable disposable's appmenus:

.. code:: console

      user@dom0:~$ qvm-features <SERVICE_QUBE> appmenus-dispvm ''

Next, set the old service qube's autostart to false, and update any references to the old one to instead point to the new in the Qube Settings of each qube as well as Global Config. For example, ``qvm-prefs work netvm <SERVICE_QUBE>`` and ``qubes-prefs default_netvm <SERVICE_QUBE``.

Named disposable for service qubes without PCI devices via command line
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


To create one that has no PCI devices attached, such as for ``sys-firewall``:

.. code:: console

      user@dom0:~$ qvm-create -C DispVM -l green <SERVICE_QUBE>
      user@dom0:~$ qvm-prefs <SERVICE_QUBE> autostart true
      user@dom0:~$ qvm-prefs <SERVICE_QUBE> netvm <NET_QUBE>
      user@dom0:~$ qvm-prefs <SERVICE_QUBE> provides_network true
      user@dom0:~$ qvm-features <SERVICE_QUBE> appmenus-dispvm ''

Next, set the old service qube's ``autostart`` to false, and update any references to the old one to instead point to the new in the Qube Settings of each qube as well as Global Config. Also make sure to update any :doc:`RPC policies </user/advanced-topics/rpc-policy>`, if needed.

Here is an example of a complete ``sys-firewall`` replacement:

.. code:: console

      user@dom0:~$ qvm-create -C DispVM -l green sys-net2
      user@dom0:~$ qvm-prefs sys-net2 autostart true
      user@dom0:~$ qvm-prefs sys-net2 netvm <NET_QUBE>
      user@dom0:~$ qvm-prefs sys-net2 provides_network true
      user@dom0:~$ qvm-features sys-net2 appmenus-dispvm ''
      user@dom0:~$ qubes-prefs default_netvm sys-net2
      user@dom0:~$ qubes-prefs updatevm sys-net2
      user@dom0:~$ qvm-prefs sys-firewall netvm sys-net2

Named disposable for service qubes with PCI devices via GUI
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


To create one with a PCI device attached, such as for ``sys-net`` or ``sys-usb``, create a :ref:`named disposable <user/how-to-guides/how-to-use-disposables:how to create named disposables>`. Write a name, choose a label and select :guilabel:`Launch Qube Settings after creation`. Click :guilabel:`Create new qube` to complete creation. When the :guilabel:`Qube Settings` opens:

- :menuselection:`Basic --> Start qube automatically on boot`
- :menuselection:`Basic --> Net qube --> (none)`
- :menuselection:`Advanced --> Virtualization --> Mode --> HVM`
- :menuselection:`Devices --> Available devices --> <DEVICE> --> >`
- :menuselection:`Services --> Select a service --> meminfo-writer --> Add`

Optionally, if this disposable will also provide network access to other qubes:

- :menuselection:`Advanced --> Provides network`

Click :guilabel:`&OK` to save changes and close the window.

On the :term:`GUI domain` terminal, disable disposable's appmenus:

.. code:: console

      user@dom0:~$ qvm-features <SERVICE_QUBE> appmenus-dispvm ''

Next, set the old service qube's autostart to false, and update any references to the old one, e.g.:

.. code:: console

      user@dom0:~$ qvm-prefs sys-firewall netvm <SERVICE_QUBE>

Also make sure to update any :doc:`RPC policies </user/advanced-topics/rpc-policy>`, if needed.


Named disposable for service qubes with PCI devices via command line
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To create one with a PCI device attached, such as for ``sys-net`` or ``sys-usb``:

.. important:: You can use ``qvm-pci`` to :ref:`determine <user/how-to-guides/how-to-use-pci-devices:\`\`qvm-pci\`\` usage>` the ``<BDF>``. Also, you will often need to include the ``-o no-strict-reset=True`` :ref:`option <user/how-to-guides/how-to-use-pci-devices:no-strict-reset>` with USB controllers.

.. code:: console

      user@dom0:~$ qvm-create -C DispVM -l red <SERVICE_QUBE>
      user@dom0:~$ qvm-prefs <SERVICE_QUBE> virt_mode hvm
      user@dom0:~$ qvm-service <SERVICE_QUBE> meminfo-writer off
      user@dom0:~$ qvm-pci attach --persistent <SERVICE_QUBE> dom0:<BDF>
      user@dom0:~$ qvm-prefs <SERVICE_QUBE> autostart true
      user@dom0:~$ qvm-prefs <SERVICE_QUBE> netvm ''
      user@dom0:~$ qvm-features <SERVICE_QUBE> appmenus-dispvm ''

Optionally, if this disposable will also provide network access to other qubes:

.. code:: console

      user@dom0:~$ qvm-prefs <SERVICE_QUBE> provides_network true

Next, set the old service qube's autostart to false, and update any references to the old one, e.g.:

.. code:: console

      user@dom0:~$ qvm-prefs sys-firewall netvm <SERVICE_QUBE>

Also make sure to update any :doc:`RPC policies </user/advanced-topics/rpc-policy>`, if needed.

Here is an example of a complete ``sys-net`` replacement:

.. code:: console

      user@dom0:~$ qvm-create -C DispVM -l red sys-net2
      user@dom0:~$ qvm-prefs sys-net2 virt_mode hvm
      user@dom0:~$ qvm-service sys-net2 meminfo-writer off
      user@dom0:~$ qvm-pci attach --persistent sys-net2 dom0:00_1a.0
      user@dom0:~$ qvm-prefs sys-net2 autostart true
      user@dom0:~$ qvm-prefs sys-net2 netvm ''
      user@dom0:~$ qvm-features sys-net2 appmenus-dispvm ''
      user@dom0:~$ qvm-prefs sys-net2 provides_network true
      user@dom0:~$ qvm-prefs sys-net autostart false
      user@dom0:~$ qvm-prefs sys-firewall netvm sys-net2
      user@dom0:~$ qubes-prefs clockvm sys-net2

Deleting disposable templates
-----------------------------


It is only possible to delete a disposable template if certain state is met:

- No disposables based on it (preloaded disposables can be ignored).
- No system or qube property links to it (such as ``template`` or ``default_dispvm``).

Let's delete a disposable template with |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> TEMPLATES --> <DISPOSABLE_TEMPLATE> --> Settings --> Basic --> Delete qube`.

Or with the command line equivalent:

.. code:: console

      user@dom0:~$ qvm-remove <DISPOSABLE_TEMPLATE>
      This will completely remove the selected VM(s)
        <DISPOSABLE_TEMPLATE>
      Are you sure? [y/N]

The deletion may fail if the qube is still referenced, in that case, proceed to the next sections.

Retire the qube from being the system's default disposable template
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


The system's default disposable template may reference the :samp:`{<DISPOSABLE_TEMPLATE>}`. Let's check if it is being used with |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> Settings (icon) --> Qubes Tools --> Qubes Global Config --> General --> Default disposable template`. Or the command line equivalent.

.. code:: console

      user@dom0:~$ qubes-prefs default_dispvm
      <DISPOSABLE_TEMPLATE>

If the :samp:`{<DISPOSABLE_TEMPLATE>}` is referenced, set an alternative, and if no alternative is available, set it to an empty value.

Retire the qube from being a qube's default disposable template
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


Now let's check the per qube ``default_dispvm`` property for any qube, in this case, the ``work`` qube, in |qubes-logo-icon|:menuselection:`Qubes App Menu (Q icon) --> APPS --> work --> Settings --> Advanced --> Default disposable template`. Or use the command line equivalent:

.. code:: console

      user@dom0:~$ qvm-prefs <QUBE> | grep default_dispvm
      default_dispvm        -  <DISPOSABLE_TEMPLATE>

If the :samp:`{<DISPOSABLE_TEMPLATE>}` is referenced, set an alternative, and if no alternative is available, set it to an empty value.

This process must be repeated for every qube that references the :samp:`{<DISPOSABLE_TEMPLATE>}`.

Disposable template deletion troubleshooting
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


If you still encounter a problem, you may have forgotten to clean an entry. Looking at the system logs will help you:

.. code:: console

      user@dom0:~$ journalctl -S 60s