Is your computer ready?

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This page provides a few tests to assess whether the software on the computer, that you have access to, is fit to allow for these tutorials.
last modified: 01:50 PM MST, Mon 31 Dec 2007

As of Fall 2005, the School of Meteorology has a computer designated for this course, gentry.metr.ou.edu. This is good news for the students in this course:

  1. Gentry will host the students' web sites, and they will have "shell access" to Gentry. Students will develop and test their programs and scripts on the machine that is also the webserver. This prevents a lot of bugs and problems.

  2. Privacy on Gentry is superior other SoM machines. Each student has a default group containing just themselves and the webserver, or apache. It is now easy to setup a password-protected website without having to worry about other users ripping off from the site by using the back door.

  3. Gentry is running the latest version of Linux, with the default shell being bash, similar to the Linux you could install on a desktop Linux.

  4. The instuctor has root access to the Gentry. It is easy for the instructor to configure Gentry specific for the course. It is easy for the instructor to help debug student programs.

  5. Gentry won't be slowed by other processes unrelated to the course.

Presumably you have followed the instructions in the page describing Requirements for METR 4330 and METR 5330 and now have a login/password for Gentry. Your password for Gentry will be different from the other SoM computers.

If students have broadband access (rather than dial-up), they may able to complete this course using a PC running Windows, with access to (or additional purchase of software) that allows for X-window forwarding. In the School of Meteorology, the most popular Windows software for X-window forwarding is offered by starnet.com. There is a discount rate for a student license. Merely installing Secure Shell on your Windows PC will allow only a command-line connection with Gentry; the lack of ability to open GUIs would be rather frustrating.

Most of the tasks for this course involve editing and running programs written in the Python language. If you go the Windows route, you may end of doing most of the text editing and program development entirely on Gentry. If the speed of the connection is fast enough, that might not cause any problems for you. You may want to attempt some of the programming within Windows, but the author of these pages never became adept at editing and running Python programs in the Windows environment, and will not be a very capable source of tech support. At some point in this course, Windows users may want to investigate the enthought distribution of Python for Windows.

A Linux installation on a local PC will allow X-window forwarding with Gentry quite naturally, as well as local program development exactly as described in the tutorials. But some additional software (e.g., Python modules) might need to be installed. The Ubuntu distribution is currently very popular, and completely free.

The SoM has some Linux computers in the plaza lab. Note: If you sit in the plaza lab and use metlabx, (metlabx=metlab1, metlab2, etc) and you see a black screen with text when you log on, be sure to enter startx. When you log off, you may need to log off twice, once from X, once from the black screen.

Here is how to connect to Gentry using secure shell (Linux, command-line example): 

ssh gentry.metr.ou.edu

If your login on your local computer is not the same as on Gentry, e. g. joestudent, or if your local computer did not forward your login, then you may need to use: 

ssh joestudent@gentry.metr.ou.edu

Connection via ssh should allow "forwarding of X-window traffic". For example, ssh will allow you to run a GUI text editor, e.g. gedit or nedit, on the monitor of your local computer. Applications that are normally run on a local desktop can often be run satisfactorily over the internet. For example, if you log onto your account in Gentry and type either eog, gedit of idle and a window pops up on your computer in five seconds or so, you are doing okay. If the attempt produces a message Error: Can't open display:, logoff and try: 

ssh -X gentry.metr.ou.edu

Here is a further test. Let's try using the python programming language on Gentry. On the command line and type python. The prompts (>>>) indicate that you are in python interpreter, meaning the computer is ready to accept python statements: 

>>> x=2
>>> x**3
>>> from pylab import *
>>> plot([1,2,4])
>>> show()
>>> quit
Alternative you can type ipython and invoke a more extensive python iterpreter. Entering ipython -pylab saves a bit or preparation to do plots: 
In [1]: plot([1,2,4])
In [2]: import Scientific.Statistics as ss
In [3]: help(ss)
      :q
In [3]: help(ss.correlation)
      :q
In [4]: ss.correlation([1,2],[-1,1])
In [5]: quit
If the delays in entering text and the opening of the plot window were acceptable to you, then your computer is ready for this course. Note: ipython is handy for exploring little bits of python code and syntax. But for lengthy program development, I use my favorite text editor to make an executable python script and then run the script from the command line. You might not need this yet: ipython manual

Cygwin

I feel the best bet to be successful with this course is to use a computer running Linux, with a broad-band connection to the internet. But there is one more option to consider: Cygwin,which offers a free and minimally invasive installation of a Linux-like operating system, as a Windows application. There is also a version called Cygwin/X, which is probably what you should grab. But I think there is no essential difference between between Cygwin and Cygwin/X, except that the setup.exe program for Cygwin/X installs all that nifty X windows stuff by default, but in Cygwin you have to need click the check box for installation of X. As of January 2006, I have had some success with using X-forwarding with Gentry from Cygwin. Here are some links to help you with Cygwin configuration: Your first test within Cygwin might go like this:
  1. I start cygwin in Windows. A terminal with a black background opens.
  2. I type: startx
  3. A window with a white background opens, a so-called "xterm". (It has an "X" icon in the upper left).
  4. In that white xterm, I enter : ssh -Y bfiedler@gentry.metr.ou.edu
  5. I tested idle, eog and gedit. They all work.
  6. To logout of gentry, I type: logout
If you are still happy with Cygwin, let's configure your xterm to have a scrollbar. Your white xterm should still be open. Presumably you are in your home Cygwin directory (type cd to be sure). Then 
cp /etc/X11/xinit/xinitrc .xinitrc
To see a listing of all your file names, including this "dot" file you just made, type ls -a in the xterm. Invoke a simple editor, for example type nedit. Then amend the last line in your .xinitrc to read: 
exec xterm -sl 1000 -sb -rightbar -e /usr/bin/bash -l
Save the change, exit nedit, and type exit to quit the xterm and X. Then restart X: in your black console type startx. The xterm should now open with a scrollbar. I find the default font size to be too tiny. To make the font larger, I type "Ctrl-rightclick" with the cursor in the white part of the xterm, and then select Large.

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