The Laboratory exists to support the Physics Department's teaching programme
in Computational Physics. Its facilities are available to all students
taking courses in the Department.
29 Dell machines with Redhat linux 7.1
operating system installed.
The CPlab is open to all registered users between the hours of 8AM and
6PM, Monday to Friday. Those wishing access to the laboratory outside these
hours should consult the Laboratory Superintendent (Liz) and fill out an
application form, which will need to be signed by your Director of Studies.
Once registered, you are able to swipe in to the lab with your matriculation
card (using your matric. card's PIN).
Outside normal hours, or when the Laboratory is being fully utilised
for a class, registered users may access the Laboratory facilities over
the network. The main CPlab machine open to network access is sybil.ph.ed.ac.uk.
Most of the material associated with CPlab-based courses is available
on World Wide Web. Access to the relevant WWW pages is, however currently
restricted to the University Campus. If you require to access these pages
from outwith the campus, see Liz McIvor for a password.
Login To log in, simply type your CPlab account name (the one that starts
with p followed by your matric. number) and password into the relevant
text boxes. Your password won't appear as it is typed so that others can't
read it.
If you've forgotten your password or don't have an account set up already,
see the lab superintendent, Liz McIvor.
Logout To log out click the IceWM button at the bottom left of the screen
(on the taskbar) and then "Logout...". You should see the dialog box below...
After making sure you've saved your files, click on OK and you'll
see the login screen again.
No; your home directory will be automatically be mounted
to whichever machine you happen to be sitting at each time you visit the
lab.
I used to login to basil/sybil, why am I logging into cplabXX now?(top)
The new cplab machines utilise local cpu and memory, rather than running
lots of sessions from a server such as Basil or Sybil. You can still access
basil/sybil by ssh'ing into them, where you will find all the same applications
as before (remember to use the "-X" ssh X-forwarding option for
graphical applications). If you are unsure about ssh, see the next section.
The program ssh (client for secure shell) emulates being at the shell prompt
of a remote machine once you are logged in. Here are examples of how to
run it:
"ssh<hostname>"
- logs into hostname as $USER (current user),
"ssh -l<username> <hostname>" - allows you to specify
a different user to login as,
"ssh -l<username> -X <hostname>" - enables
X-forwarding for running graphical applications remotely.
The taskbar resides at the bottom of the screen once you are logged in.
It is a tool for managing your desktop. The desktop is the environment
where your windows (e.g. Netscape, Xterm, etc.) can be resized, moved,
iconified, maximised, layered, etc. From left to right, the taskbar shows:
a shortcut menu button, shortcuts to XTerm and Netscape, shortcuts to your
other desktops, a list of open application windows and the time. It should
look something like this...
By clicking on the IceWM shortcut menu button you'll see a list of categories
of shortcuts to programs. Note: You can also access this menu by
pressing CTRL and ESC keys together or by left-clicking anywhere
on your desktop.
For example if you wanted to run ghostview you could click on Apps
and then Ghostview.
By clicking on the Terminal or Netscape logos next to the IceWM button
an XTerm or Netscape window will open.
The numbered desktops (1...4) are extra space for putting windows. For
example, if you have too many windows open one desktop area might become
cluttered so you could send some of the windows to desktop 2. You can move
a window to another desktop by clicking the upper-left most button on a
window and then selecting Move To..
To access the shell prompt, which is an important aspect of linux, simply
click on the XTerm button next to the IceWM shortcut menu button. Its the
one with a picture of a computer on it.
A window will appear, which looks like this (perhaps a little larger):
You can now interact textually with linux. You can find out more about
commands in this tutorial.
You have your own personal (home) directory in /Home/$USER which
is located on sybil/basil, a remote network file server for the Physics
department. In order to save files in that directory, preceed the filename
with '~/<filename>' where '~' represents the path
to your home directory.
Alternatively, you can save files to the 'scratch' space on your machine
(see next section).
There is a large partition on each machine in the CPlab that is mounted
to /scratch (ie. its path). Its purpose is for users who need more
disk space than their quota provides to store temporary files. As every
machine has its own /scratch directory, the files you save there will only
be available on that machine. THIS DATA IS NOT BACKED UP and may be lost
in the event of a system failure. Do not store important data here.
Your home directory looks the same on every machine in the CPlab as it
is mounted from sybil/basil. Your quota is the amount of disk space on
sybil/basil that has been allocated to you. To find out what your quota
is and how much of it you have left, simply type 'quota' at the
shell prompt (e.g. XTerm).
If you feel you need to have your quota allocation reviewed, speak to
the lab superintendent (Liz).
The application Ghostview can be used for viewing Postscript files
and is found on the shortcut menu under Apps (see section above on 'The
Taskbar'). For PDF (Portable Document Format) files, Acrobat Reader can
be used and is also found in the shortcut menu under Apps.
To run Ghostview or Acrobat Reader from the shell prompt type:
In order to set the desktop wallpaper you will need to create a directory
in your home directory called ".icewm" (type "mkdir ~/.icewm") and
copy the local file /usr/X11R6/lib/X11/icewm/preferences into it
(type "cp /usr/X11R6/lib/X11/icewm/preferences ~/.icewm/"). The
reason for this is that when you login, icewm will look for its configuration
files first in ~/.icewm. If the directory doesn't exist, it proceeds
to load its default configuration instead.
Insert the line,
DesktopBackgroundImage="path
to your file" and change the file to be used to your own.
Tip: To create a '.xpm' image file from a '.jpg',
use gimp to save your 'foo.jpg' as 'foo.xpm'
You can also read the IceWM
manual, which provides a full description of the configuration files.
We prefer a window manager that can be utilised across the range
of machine platforms we run in the department (Sun, Linux); at present
IceWM is the most suitable.
To access your floppy disk, first you need to mount it to a mount point
(a directory that will act like the root node of the tree of the file system
being mounted). For example, to mount a floppy disk, type:
"mount /mnt/floppy"
To mount a cd, follow the above steps for a floppy and replace "floppy"
with "cdrom".
Now you can access your floppy with "cd /mnt/floppy".
There are CD writers installed on 5 machines in CPlab, cplab25 to
cplab29. These computers are located at the back of the lab and can be
used by anyone who has acess to the lab.
To write a cd you will need to use an application called "xcdroast".
The first time you load roast you will get an error telling you that you
don't have a configuration file. There is no need to worry however, to
fix this simply click on the setup then save configuration buttons. Exit
roast and start it again and you will never have to worry about it again.
There are several ways to write a cd:
1) To write a cd from an iso disk image ( will have a .iso file extension
ie image_name.iso):
You need to copy the image to the
directory /scratch/CD to do this type :
cp
image_name.iso /scratch/CD/image_name.iso
Next start up xcdroast and click the "create cd" button . You should see
the name of your image in the "image information box" .
Now click the "write tracks" button followed by the "Layout tracks" tab.
Once again you should see your disk image name
Select your image and click "add" and "accept layout"
Finally click the write tracks button upon which you will be prompted to
insert a blank cd. Do this and your cd will write
2) To duplicate an existing cd :
Put the cd to be duplicated in the computer and run xcdroast.
Click on the "create cd" button NOT the "duplicate cd button"
Go to the "read tracks" screen and you should see your cd's name in the
cd information box.
Click "select all" and then "read selected tracks". A dialog box will come
up telling you that it is reading the cd. After about 5 minutes it should
be finished.
At this point click ok and enter the "write tracks" screen. Go to the "layout
tracks" tab and select the name of your cd. Click "accept layout".
Finally click the write tracks button upon which you will be prompted to
insert a blank cd. Do this and your cd will write
3) To write a cd from files on your hard disk:
Click on the Master Tracks button and make sure the "display directories
only" button is unchecked
Use the "File/directory view " window to find the files you want to write
and when you have clicked on the press add.
You will be asked where you want your files to be located on the cd. Click
the box of you prefer and then ok.
Repeat the above two steps for all the files you want to add.
When you are happy with all your files click the "iso header" tag where
you can add additional information about your cd.
The most important of these is the volume id box where you cant enter the
name of your cd.
Click on the "Create session/image" tag and use the "Calculate size" button
to make sure your files are less than 700MB(ie will fit on the CD)
Finally place a CDWR/CDR in the drive and click the "Master and write on-the-fly"
button and your cd should write.
