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 a partially proprietary operating system maintained by Apple Computer and used by most of their products. It is also known as macOS, iOS, etc. depending on the exact variant. Older versions were called “Mac OS X.”
By default the file system will be case insensitive, albeit case preserving. This can cause nasty problems: for instance, the installation attempt for a package having an INSTALL file can result in ‘make install’ reporting that nothing is to be done!
Darwin does support case-sensitive file systems, but they must be
formatted specially as such, and Apple discourages use of a
case-sensitive volume for the base operating system. To build software
that expects case-sensitive filenames, it is best to create a separate
disk volume or disk image formatted as case sensitive; this can be done
using the diskutil command or the Disk Utility application.
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. 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.