Don’t be afraid of command line! It is friendly and powerful tool. Practically identical is command line also in Mac OS X, BSD and another UNIX-based systems, not only in Linux. Basic knowledge of Linux is not conditional. Course will be taught in Linux, but most of the point are applicable also for another UNIX systems like Mac OS X. Knowledge of Linux/UNIX is useful e.g. for working with molecular and another data. MetaCentrum is service provided by CESNET allowing access to huge computational capacity.