Linux is a open source implementation of the Portable Operating System (POSIX) standard. It is a cousin to the Solaris, IRIX, MacOS X and BSD operating systems. Because it is easy to customize, requires modest resources, and offers high levels of stability and scalability, Linux has become ubiquitious in high performance scientific computing. The version of Linux running on the SIRAF cluster is Scientific Linux, a version of Red Hat Enterprise Linux customized by researchers at Fermi National Accelerator Laboratory (FNAL).
Most users will access the cluster via the NoMachine nxclient remote desktop application. The two most popular Linux desktop environments are KDE and GNOME. Both offer similar applications and range of functions; which one to use is a matter of taste and applications from one can run on the other.
The KDE User Guide and FAQ are available online and in PDF format on the KDE Documentation site. The current version of KDE installed on the SIRAF cluster is 3.5.4.
The GNOME User Guide is available online and as a single HTML file download via the GNOME Documentation Library. The current version of GNOME installed on the cluster is 2.16.
Some skill in using the Linux command line interface (CLI) is necessary for submitting batch jobs to the cluster and automating file/data processing operations. The command line interface is also known as the "shell". The default shell in Linux is the Bourne-Again shell (bash), however most users are assigned the Z shell (zsh) because it has more basic and advanced features and is more memory efficient. Both shells attempt to mimic the official POSIX shell and have options to enforce compliance. Because of numerous past security problems, users cannot change their shell on their own and instead should notify the cluster administrator (email to c-chan_at_uchicago.edu) if they would like to change to a different shell.