Show if user is also a POSIX user in edit user form.

actions/check-user-exists

@@ -0,0 +1,28 @@
+#!/bin/sh
+#
+# This file is part of Plinth.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+# Can be run as normal user.
+
+username="$1"
+
+getent passwd "$username" >/dev/null
+if [ $? -eq 0 ]; then
+    echo "User exists"
+else
+    echo "User does not exist"
+fi

plinth/modules/users/templates/users_update.html

@@ -46,6 +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 %}
+
         <input type="submit" class="btn btn-primary" value="Save Changes"/>
 
       </form>

plinth/modules/users/views.py

@@ -26,6 +26,7 @@ from django.views.generic import ListView
 from gettext import gettext as _
 
 from .forms import CreateUserForm, UserUpdateForm, UserChangePasswordForm
+from plinth import actions
 
 
 subsubmenu = [{'url': reverse_lazy('users:index'),
@@ -70,6 +71,12 @@ class UserUpdate(ContextMixin, SuccessMessageMixin, UpdateView):
     success_message = _('User %(username)s updated.')
     title = _('Edit User')
 
+    def get_context_data(self, **kwargs):
+        context = super(UserUpdate, self).get_context_data(**kwargs)
+        output = actions.run('check-user-exists', [self.object.username])
+        context['is_posix_user'] = 'User exists' in output
+        return context
+
     def get_success_url(self):
         """Return the URL to redirect to in case of successful updation."""
         return reverse('users:edit', kwargs={'slug': self.object.username})