Hi,

Please can you elaborate the question.

Cheers,
Shazin

Well, technically Linux is "NOT" a UNIX. It uses the Linux kernel and the GNU userland utilities. As such GNU stands for "Gnu's Not Unix" and instead is a UNIX-like operating environment.

Also, while AIX, Solaris, BSD, HP-UX and even Mac OSX are "UNIX" depending on the actual certification from whoever holds the rights to determine what UNIX is, many people lump them together as the tools are similar and the commands are similar in most cases.

In the case of a distribution, that is due to the maintainer's decisions of what to include, how to control the releases, etc.

SUSE, Debian, Red Hat, are all using the Linux kernel, GNU userland, etc, however Debian uses different package management, for the most part, Different run levels and configuration files are employed, and the choice of what goes into a release is left up to the maintainer of each distribution.

It's a kernel that, together with GNU, makes a system that fits quite a lot of the UNIX specification. The backronym is an obsolete joke, and there is no extant Real UNIX©®™ operating system and hasn't been for a long time, so I'd love to hear a reason beyond "well, it's not directly descended from BSD" for the constant parroting I hear of this...

What is UNIX ?

You can read for yourself.


There is also a mark, or brand, that is used to identify those products that have been certified as conforming to the Single UNIX Specification, initially UNIX 93, followed subsequently by UNIX 95, UNIX 98 and now UNIX 03.

Distribution means a certain set of applications that are bundled and pre-configured. The difference in that for Linux distributions (or distros) can range from almost nothing (eg. RHEL vs. CentOS), to a completely different intention, and thus software selection (eg. Slackware vs. Mint)

Different "flavours" are called that because they are based on the same principles (POSIX, Single UNIX Specification), but follow different ways for implementation. For example, while all Unices have a sigaction system call, probably none of them share the same implementation, as the Kernel itself follows different specifications.

I hope I helped clear some of the confusion.