Department of Physics

Linux

The CIS use Debian as their linux operating system. This can be accessed through any PC attached to the CIS Network PC Service, either directly, if they are dual boot machines (as in the Physics computer classroom), or via Windows.

How to logon to Linux: The best way to access the CIS Unix from the PCs in the Physics classroom is to boot debian directly from the start-up screen immediately after the computer has been switched on. You will get a login prompt for your CIS Username and password, just like under Windows. This runs linux locally on your PC. Failing that, you can use the provided X2Go software under Windows to connect remotely to the CIS linux server (mira.dur.ac.uk). You can find this under `All programs' -> `Durham Network' -> 'Connect to CIS linux' in the `Start' menu. An X2Go window will appear, inside which is a login prompt for your CIS Username and password. Once you have logged in a new window will appear containing your linux desktop.

If you are familiar with Microsoft Windows or Mac OS X, you will find Linux somewhat different. Linux (which comes in various versions, the CIS currently use Debian) is first and foremost a command-line based operating system, which means you type in commands at a prompt on your terminal and hit the return key to get them to run. H owever, by using a windowing program such as GNOME you can have both the convenience of a graphical interface like Windows and the flexibility of the command-line. Nevertheless, Linux is not Windows and you may find yourself doing most of your work by typing in commands.

Linux has a nasty habit of overwriting existing files without warning you, and it is also very easy to delete files without meaning to. To help avoid this we strongly recommend editing your .cshrc file (note the leading dot!), found in your home directory, to contain the following lines:

alias cp   'cp -i'
alias mv   'mv -i'
alias rm   'rm -i'

Now when you attempt to copy, rename or delete files you will be prompted as to whether you really meant to do it. This will only take effect from when you next login - to get it to have immediate effect in the terminal window you are working in type source .cshrc

Logging in from outside the University You can access mira (and hence your files) from anywhere in the world, at any time. You just need an ssh client on your machine. For Windows, putty will suffice. Linux already has the slogin or ssh commands. slogin yourusername@mira.dur.ac.uk This only gives you command line access. To run graphics you would probably need fibre broadband speeds (and if your are on Windows, an X-client).

Resources

Please remember that you are sharing mira with the rest of the University, so please do not hog all the resources (CIS will come looking for you if you do!). Rather than tying up a terminal for hours on end (and risking disconnection), the recommended way of running long jobs is to use the screen command - see http://www.rackaid.com/blog/linux-screen-tutorial-and-how-to/ for a tutorial.

Editing

There are lots of Linux editors, and if you are already familiar with one use that. Python is often bundled with an integrated editor called IDLE. This is OK, but you may be better off using a dedicated text editor instead (such as emacs, which is the most popular linux editor). As with most other linux commands, these can be started directly by typing in the name of the editor on the command line.

Disk space

All CIS Linux machines share a common disk filestore on which you will have a permanent allocation of space (your `file quota' - to show your quota on linux use the command quota -v), so you will be able to access your files from any CIS machine. Also, your PC J: drive is the same as your Linux home directory, so you can see your files from a PC as well. Note that some projects can produce large files, and if you are not careful it is easy to exceed your allowed quota! Temporary filespace is available in this event, or you can request that CIS increase your quota.

Fortran

Fortran has a long history of being used for the computationally intensive tasks involved in physics.

CIS has a couple of guides available that can help you get started: