Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
From version 2.6 onward, Linux supports ACLs. ACLs extend the traditional UNIX file permissions model, allowing file permissions to be controlled on a per-user and per-group basis.
The final versions (Draft 17) of the draft POSIX.1e and POSIX.2c standards are available online at http://wt.tuxomania.net/publications/posix.1e/.