Linux Teaching Lab at the Department of Computer Science - FAQ
What is X11 forwarding?
X11 forwarding passes as X11 client display
to your local computer from a remote system. This forwarding is done by default by ssh on most
systems if you are running a local X server. It makes it possible for you
to run applications on a remote computer and display them on your local
or home computer. You can then use the application as if you were sitting
in front of the remote computer.
How do I get an X server?
If you are running Linux, you already have one. The graphical
environment that you log into is X11 based. You don't need to do anything.
If you are running Windows, we recommend cygwin.
Just be sure to tell the installation program to install Everything. By default,
it does not install everything you need to have a functional X server.
As for MacOS there is a very good free X server for MacOS X from Apple
How can I print?
The CSIC linux lab does not have any print
facilities of its own. Students will have to utilize other print
resources on campus. Please
refer to OIT's
documentation on their print system and use scp or sftp
to transfer files to your wam account to
print.
How can I tell how much of my quota I have
used?
Use fs listquota:
derek@squeamish:~> fs listquota
Volume
Name
Quota Used
%Used Partition
staff.derek
10000000
300566
3% 2%
What is this directory called .backup in the
base of my home directory?
The .backup directory is a snapshot of your data from the
previous night.
If you delete something from your home
directory, you can recover it from this directory.
Note:
If you create a file during the day and then
delete it later in the day it will not be in the .backup because the
filesystem does not take the snapshot until early in the morning
(2-3am). If you don't recover your files within 24 hours then the
next snapshot will discard them, so if you delete a file you should
look in the .backup directory right away.
What if my credentials/tokens run out and I
can't get in my home directory anymore?
Your credendials are good for 10 hours from the time
you log in. If you need to get new credentials you can run the
/usr/local/bin/csiclogin program. This program will prompt you
for you password and issue you credentials
for another 10 hours. You should then be able to cd back
to your home directory.
Why can't I use
ssh_authorized keys to get into my account?
Because the cluster is based on AFS. Your home
directory exists in AFS which will not allow you access to your home
directory until you have the proper token to access it, this requires
having a Kerberos5 credential which is retrieved by typing your
password and then converting that credential into a AFS token.
Since ssh does not run with any sort of credentials itself, it will not
be able to get access to you home directory to get to the authorized
keys file let alone have the Kerberos5 creds to make a token. So
because of the design of the system to be secure this will not work.
How can I
choose a different window manager?
There are 3 default window managers, GNOME,
KDE and XFCE. These can be selected by choosing the session
button on the login screen and selecting one of them. By default
GNOME is the default window manager. To choose another window
manager that has been installed (in /usr/local there is fluxbox, fvwm2,
windowmaker, gnome-2.6, kde-3.2, kde-3.3) you need to create a
~/.xsession file that is executable by you in your home
directory. In that you can put one of the window managers that is
in /usr/local or that you have installed to run by putting the full
path to the startup executable. You may need to set
LD_LIBRARY_PATH's and search paths. Then you can choose the
default selection from the session button at the login screen.
