~azzar1/unity/add-show-desktop-key

.. IVLE - Informatics Virtual Learning Environment

   Copyright (C) 2007-2009 The University of Melbourne

.. This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 2 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 General Public License for more details.

.. You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

.. _ref-faq:

**************************

Frequently Asked Questions

**************************

This is a list of Frequently Asked Questions for IVLE. It answers questions 

about common issues encountered when configuring or running the system.

.. _ref-faq-how:

How can I...

============

... change the Terms of Service notice?

---------------------------------------

You should customize the ToS notice at :file:`/var/lib/ivle/notices/tos.html`.

... delete a user from IVLE?

----------------------------

This is usually a bad idea since it requires all the references to that user 

to be removed from IVLE. This may have unintended consequences particularly 

with groups or projects but might be required in installations where an 

existing login conflict with a new login (typically encountered when usernames 

are recycled).

The steps to completely remove a user would be:

1. Disable the users account

2. Unmount the users jailmount directory (typically 

   :file:`/var/lib/ivle/jailmounts/LOGIN`)

3. Backup the user's files (typically :file:`/var/lib/ivle/jails/LOGIN`) and 

   remove this directory.

4. Backup the user's repository (typically 

   :file:`/var/lib/ivle/svn/repositories/users/LOGIN` on the subversion 

   server) and remove this directory.

5. Make a backup of the IVLE database (``sudo -u postgres pg_dump ivle > 

   backup.sql``)

6. Either change the users login (``UPDATE login SET login='NEWLOGIN' WHERE 

   login='LOGIN'``) or remove all references to this login in the database

The following lines of SQL should remove all traces of a user ``LOGIN`` from 

the database::

    BEGIN TRANSACTION;

    DELETE FROM exercise_save USING login WHERE

        exercise_save.loginid = login.loginid AND login.login = 'LOGIN';

    DELETE FROM exercise_attempt USING login WHERE

        exercise_attempt.loginid = login.loginid AND login.login = 'LOGIN';

    DELETE FROM project_mark USING login WHERE marker = login.loginid AND

        login.login = 'LOGIN';

    DELETE FROM project_submission USING login WHERE

        submitter = login.loginid AND login.login = 'LOGIN';

    DELETE FROM project_extension USING login WHERE

        approver = login.loginid AND login.login = 'LOGIN';

    DELETE FROM assessed USING login WHERE

        assessed.loginid = login.loginid AND login.login = 'LOGIN';

    DELETE FROM enrolment USING login WHERE

        enrolment.loginid = login.loginid AND login.login = 'LOGIN';

    DELETE FROM group_member USING login WHERE

        group_member.loginid = login.loginid AND login.login = 'LOGIN';

    DELETE FROM group_invitation USING login WHERE

        (group_invitation.loginid = login.loginid OR

        inviter = login.loginid) AND login.login = 'LOGIN';

    DELETE FROM project_group USING login WHERE createdby = login.loginid AND

        login.login = 'LOGIN';

    DELETE FROM login WHERE login='LOGIN';

    COMMIT;

If you do not want to lose group data, a better option may be to reassign the 

user ``LOGIN``'s groups to ``NEWLOGIN`` (one possible option would be to 

create and use a 'nobody' account)::

    BEGIN TRANSACTION;

    DELETE FROM exercise_save USING login WHERE

        exercise_save.loginid = login.loginid AND login.login = 'LOGIN';

    DELETE FROM exercise_attempt USING login WHERE

        exercise_attempt.loginid = login.loginid AND login.login = 'LOGIN';

    UPDATE project_mark SET marker = l2.loginid FROM login AS l1, login AS l2

        WHERE marker = l1.loginid AND l1.login = 'LOGIN' AND l2.login = 

        'NEWLOGIN'

    DELETE FROM project_submission USING login WHERE

        submitter = login.loginid AND login.login = 'LOGIN';

    UPDATE project_extension SET approver = l2.loginid FROM

        login AS l1, login AS l2 WHERE approver = l1.loginid AND

        l1.login = 'LOGIN' AND l2.login='NEWLOGIN';

    DELETE FROM assessed USING login WHERE

        assessed.loginid = login.loginid AND login.login = 'LOGIN';

    DELETE FROM enrolment USING login WHERE

        enrolment.loginid = login.loginid AND login.login = 'LOGIN';

    DELETE FROM group_member USING login WHERE

        group_member.loginid = login.loginid AND login.login = 'LOGIN';

    DELETE FROM group_invitation USING login WHERE

        group_invitation.loginid = login.loginid AND login.login = 'LOGIN';

    UPDATE group_invitation SET inviter = l2.loginid FROM

        login AS l1, login AS l2 WHERE inviter = l1.loginid AND

        l1.login = 'LOGIN' AND l2.login='NEWLOGIN';

    UPDATE project_group SET createdby = l2.loginid FROM

        login AS l1, login AS l2 WHERE createdby = l1.loginid AND

        l1.login = 'LOGIN' AND l2.login = 'NEWLOGIN';

    DELETE FROM login WHERE login='LOGIN';

    COMMIT;

.. _ref-faq-why:

Why does...

===========

... Apache not restart?

-----------------------

Make sure no console processes are lying around (e.g. sudo killall

python), then restart with ``sudo /etc/init.d/apache2 restart``.  If the issue

persists, try stopping the server and starting it in two separate

steps, so you see the errors reported by the start script.

... IVLE dump me back to the login screen with no error when I try to login?

----------------------------------------------------------------------------

This is usually because IVLE can't save your session information. IVLE saves

sessions to a sessions directory on disk. Unfortunately, this is not currently

configurable in :file:`./setup.py` config. You need to edit the Apache config 

file.

Look for ``PythonOption mod_python.file_session.database_directory``. Make

sure it is set to the place you want. Then, you need to manually make sure

that directory exists.

The default is :file:`/var/lib/ivle/sessions`.

... ivle-buildjail fail with 'Error: Jail contains world writable path'

-----------------------------------------------------------------------

When running :program:`ivle-buildjail` you may occasionally see an error 

like::

    Error: Jail contains world writable path: 

    '/var/lib/ivle/jails/__base_build__/tmp/.ICE-unix'.

    This is a security vulnerability as jail template contents are shared 

    between users. Please either make this path world unwriteable or remove it 

    from the jail.

This means that writable files exist in the Jail template. If left in the jail 

then users would be able to edit a file that is shared between all jail 

instances. The usual solution is just to remove these file from the jail build 

directory and try again.

At present it is not possible to include world writable files outside a user's 

home directory so if this file is deliberately included you will need to 

ensure that it is not world writeable.

... the console return 'Console Restart' messages

-------------------------------------------------

There are three cases where a console may be restarted:

1. **Console Restart: The IVLE console has timed out due to inactivity**

    The Python console process is no longer running. This is most likey due to 

    the console process being automatically terminated due to no messages 

    being sent or received by the console in the previous 15 minutes.

    This message can also be triggered if the console is terminated for 

    another reason (such as being sent :const:`SIGKILL` from the system 

    command line or any other fatal signal).

2. **Console Restart: CPU Time Limit Exceeded**

   To prevent exhaustion of local system resources, Python console processes 

   are set with an CPU Time Limit of 25 seconds of user time (time executing 

   on the CPU rather than real "clock-on-the-wall" time).

   This setting can be configured by changing the values associated with 

   :const:`RLIMIT_CPU` in :file:`bin/trampoline/trampoline.c`.

3. **Console Restart: Communication to console process lost**

    IVLE was unable to understand a response from the console process. This 

    will only happen if the console sends a malformed response and quite 

    likely a bug.

4. **Console Restart: Communication to console process reset**

    IVLE's TCP connection to the console process was reset. May indicate 

    network issues.