users: Add posix user messages to other user management forms

- Slightly modify the message in user update form

plinth/modules/first_boot/forms.py

@@ -48,8 +48,11 @@ than 63 characters in length.'),
             'password': forms.PasswordInput,
         }
         help_texts = {
-            'username': _('Choose a username and password to access this web\
- interface. The password can be changed and other users can be added later.'),
+            'username':
+            _('Choose a username and password to access this web interface. '
+              'The password can be changed and other users can be added '
+              'later. A POSIX system user with administrative privileges '
+              '(sudo) is also created.'),
         }
 
     def save(self, commit=True):

plinth/modules/users/templates/users_change_password.html

@@ -31,6 +31,12 @@
 
         {{ form|bootstrap }}
 
+        {% if is_posix_user %}
+        <p>This user is also a POSIX system user and password for POSIX system
+          user will also be updated.
+        </p>
+        {% endif %}
+
         <input type="submit" class="btn btn-primary" value="Save Password"/>
 
       </form>

plinth/modules/users/templates/users_delete.html

@@ -24,6 +24,12 @@
 
   <h3>Delete User <em>{{ object.username }}</em></h3>
 
+  {% if is_posix_user %}
+  <p>This user is also a POSIX system user.  POSIX system user will also be
+     deleted.
+  </p>
+  {% endif %}
+
   <p>Delete user permanently?</p>
 
   <form class="form" method="post">

plinth/modules/users/templates/users_update.html

@@ -46,10 +46,11 @@
 
         {{ form|bootstrap }}
 
-	{% if is_posix_user %}
-	<p>This user is also a POSIX user and (if active) can log in to the
-	  system through SSH.</p>
-	{% endif %}
+        {% if is_posix_user %}
+        <p>This user is also a POSIX system user and, if active, can log in to
+          the system through SSH.
+        </p>
+        {% endif %}
 
         <input type="submit" class="btn btn-primary" value="Save Changes"/>
 

plinth/modules/users/views.py

@@ -94,6 +94,13 @@ class UserDelete(ContextMixin, DeleteView):
     success_url = reverse_lazy('users:index')
     title = _('Delete User')
 
+    def get_context_data(self, **kwargs):
+        """Return the data to be used for rendering templates."""
+        context = super(UserDelete, self).get_context_data(**kwargs)
+        output = actions.run('check-user-exists', [self.kwargs['slug']])
+        context['is_posix_user'] = 'User exists' in output
+        return context
+
     def delete(self, *args, **kwargs):
         """Set the success message of deleting the user.
 
@@ -119,6 +126,13 @@ class UserChangePassword(ContextMixin, SuccessMessageMixin, FormView):
         kwargs['user'] = User.objects.get(username=self.kwargs['slug'])
         return kwargs
 
+    def get_context_data(self, **kwargs):
+        """Return the data to be used for rendering templates."""
+        context = super(UserChangePassword, self).get_context_data(**kwargs)
+        output = actions.run('check-user-exists', [self.kwargs['slug']])
+        context['is_posix_user'] = 'User exists' in output
+        return context
+
     def get_success_url(self):
         return reverse('users:edit', kwargs={'slug': self.kwargs['slug']})