From your PC you should be able to connect to UNIX server and display full screen output back on the local machine.
Use of the web is now an essential part of everyday activity. It is highly unlikely that you are unfamiliar with any aspect of Web usage.
You should be able to perform basic files operations. You should understand what environmental variables are and about aliases and what part the special files .login and .bashrc play in defining them. Knowing a little basic shell programming would also be useful.
There will be a lecture on our Linux (a form of UNIX) server .
An introductory course in Python and C++ will be given, as these are the most useful languages currently.
Some older experiments still have a large FORTRAN code base. If FORTRAN is new to you then working through the FORTRAN introduction at:-
http://www-pnp.physics.ox.ac.uk/~gronbech/intfor/
would be a good idea. If you do know FORTRAN, why not take a crack at one of the exercises listed at the end of the FORTRAN introduction?
LATEXis a document preparation system that is liked by some and loathed by others. However it is still used for papers and the chances are you will use it to write your thesis. There is a very brief introduction in 10.3.2. If you want to know more now, talk to your experiment colleagues.
This is a general purpose analysis tool and framework that is mostly written in C++. It is heavily used to look at and manipulate experimental data.