This section aims at presenting some systems and pointers to documentation. It may help you addressing particular problems reported by users.
Posix-conforming systems are derived from the Unix operating system.
The Rosetta Stone for Unix contains a table correlating the features of various Posix-conforming systems. Unix History is a simplified diagram of how many Unix systems were derived from each other.
The Heirloom Project provides some variants of traditional implementations of Unix utilities.
Darwin is also known as Mac OS X. Beware that the file system can be case-preserving, but case insensitive. This can cause nasty problems, since for instance the installation attempt for a package having an INSTALL file can result in ‘make install’ report that nothing was to be done!
That’s all dependent on whether the file system is a UFS (case sensitive) or HFS+ (case preserving). By default Apple wants you to install the OS on HFS+. Unfortunately, there are some pieces of software which really need to be built on UFS. We may want to rebuild Darwin to have both UFS and HFS+ available (and put the /local/build tree on the UFS).
QNX is a realtime operating system running on Intel architecture meant to be scalable from the small embedded systems to the hundred processor super-computer. It claims to be Posix certified. More information is available on the QNX home page.
Officially this was called the “Seventh Edition” of “the UNIX time-sharing system” but we use the more-common name “Unix version 7”. Documentation is available in the Unix Seventh Edition Manual. Previous versions of Unix are called “Unix version 6”, etc., but they were not as widely used.