============
Cheat sheets
============

systemd's dependencies
======================

``A`` has ``X=B`` in its ``[Unit]`` section where ``X`` is one of ``Wants``,
``Requires``, ``Requisite``, ``BindsTo``, ``PartOf``, and ``Upholds``.

+--------------------------+--------------+-------------+-------------------------------------------------+
|                          | ``A`` starts | ``B`` fails | ``B`` stops / restarts                          |
|                          |              |             +------------------------+------------------------+
|                          |              |             | implicitly             | explicitly             |
+==========================+==============+=============+========================+========================+
| ``Wants``                | ``B`` starts |             |                                                 |
+--------------+-----------+--------------+-------------+------------------------+------------------------+
| ``Requires`` | ``After`` | ``B`` starts | ``A`` fails |                        | ``A`` stops / restarts |
+--------------+-----------+--------------+-------------+------------------------+------------------------+
| ``Requires`` |           | ``B`` starts |             |                        | ``A`` stops / restarts |
+--------------+-----------+--------------+-------------+------------------------+------------------------+
| ``BindsTo``  | ``After`` | ``B`` starts | ``A`` fails | ``A`` stops / restarts | ``A`` stops / restarts |
+--------------+-----------+--------------+-------------+------------------------+------------------------+
| ``BindsTo``  |           | ``B`` starts | ``A`` exits | ``A`` stops / restarts | ``A`` stops / restarts |
+--------------+-----------+--------------+-------------+------------------------+------------------------+
| ``PartOf``               |              |             | ``A`` stops / restarts | ``A`` stops / restarts |
+--------------------------+--------------+-------------+------------------------+------------------------+
| ``Upholds``              | ``B`` is     |             |                        |                        |
|                          | kept alive   |             |                        |                        |
+--------------------------+--------------+-------------+------------------------+------------------------+

``Requisite``: ``A`` starts normally if ``B`` is already running, fails otherwise.