Install options explained in readme

README.rst

@@ -216,10 +216,22 @@ Customize
   behaviour, and for instance attribute a default entrance year.
 
 Initial migration
-  If you used allauth without LongTermClipperAccountAdapter, or another CAS
+  Description
-  interface to log in, you need to update the Users to the new username policy,
+    If you used allauth without LongTermClipperAccountAdapter, or another CAS
-  and (in the second case) to create the SocialAccount instances to link CAS and
+    interface to log in, you need to update the Users to the new username policy,
-  Users. This can be done easily with ``$ python manage.py install_longterm``.
+    and (in the second case) to create the SocialAccount instances to link CAS and
+    Users. This can be done easily with ``$ python manage.py install_longterm``.
+
+  Install_longterm options
+    - ``--use-socialaccounts``: Use the existing SocialAccounts rather than all the Users. Useful if you are already using Allauth and don't want ``install_longterm`` to mess with the non-clipper authentications.
+    - ``--keep-usernames``: Do not apply the username template (e.g. ``clipper@promo``) to the existing accounts, only populate the SocialAccounts with LDAP informations. Useful if you don't want to change the usernames of previous users, but do want such a template for future accounts.
+    - ``--clipper-field <field_name>``: Use a special field rather than the username to get the clipper username (for LDAP lookup and SocialAccount creation/update). This parameter is compatible with ForeignKeys (e.g. ``profile.clipper``). Note: ``--use-socialaccounts`` will ignore the ``--clipper-field`` parameter.
+    - ``--fake``: Do not modify the database. Use it to test there is no conflict, and be sure the changes are the ones expected. This command does not check for uniqueness errors, so there it may succeed and the actual command fail eventually.
+
+  Typical use cases
+    - *Django-cas-ng -> Longterm*: Use ``install_longterm`` without parameters, or maybe ``--keep-usernames``. If you had a custom username handling, ``--clipper_field`` may be useful.
+    - *Allauth -> Longterm*: Use ``install_longterm`` with ``--use-socialaccounts``, and maybe ``--keep-usernames``.
+
 
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 Demo Site