Official site; news, support, documentation, whitepapers, downloads, consulting, training, embedded solutions.

http://redhat.com [ embedded solutions ]

    Comprehensive information and resources about the Linux Operating System.

http://www.linux.org [ Linux Operating System ]

    Leverage our robust operating system training and keep your skills sharp. Courses and certifications include Red Hat® Linux™ training and certification, Microsoft MCSE training and certification, AIX training and AIX certification, Clarity training, IBM training, and UNIX training.

http://www.globalknowledge.com/ [ Operating System Training ]