Operating systems and Linux distributions
 Operating Systems
GNU/Linux aims to be a free and open-source unix (or unix-like) operating system that will run on most types of computer hardware and uses an X11 graphical user interface. Various distributions of GNU/Linux exist that have different package management systems and other features. Most of these are ideal platforms for X-ray crystallography and other scientific computational requirements.
 Linux Distributions
- Red Hat with its clones CentOS and Scientific Linux (binary compatible; produced from the source provided by Red Hat)
- OpenSuse will run most Red Hat and Fedora packages
These differ greatly in the time they support their releases:
- OpenSuse: 2 years
- Fedora: 18 months
- Ubuntu: 18 months
- Ubuntu LTS: Server 5 years, Desktop 3 years
- RedHat, CentOS, Scientific Linux: 7 years
- Gentoo: less relevant; "rolling releases"
- Debian: 1 year after a new release; thus usually 2.5 - 3.5 yrs
- SUSE Linux Enterprise Server: see http://support.novell.com/lifecycle/lcSearchResults.jsp?st=suse+linux+enterprise+server; generally 6 years or more
 Useful Links
 Mac OS X
Mac OS X is a proprietary BSD-unix-derived operating system that runs on Apple's computers. The BSD-subsystem, called Darwin, attempts to be open-source. Unlike most other flavors of unix, OS X is not based on an X11 windowing system, but instead uses a proprietary Aqua graphical user interface. For crystallographers and others who need the conventional X11 windowing system, an Xserver for OS X is available, and installs by default on the most current version of OS X.
- Apple's Mac OS X Unix page.
 Irix (SGI)
By all accounts, SGIs are now obsolete. They are more expensive and perhaps offer higher productivity, but it is not worth the money when $500 Linux box takes 1/2 hour to calculate a simulated annealing omit map. There are some examples of software (such as GRASP) that you can only run on SGIs, not Linux. O is also wicked fast on SGIs.
Irix is a flavor of UNIX and is still supported by SGI.
 See also