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Is Linux really like Unix?

Depends on the distribution but for the most part yes. Slackware is considered the most unix-like (well, according to them anyway... ). Debian may be more unix-like as well but I've only had limited experiece with it.

Steel wrote:

Depends on the distribution but for the most part yes. Slackware is considered the most unix-like (well, according to them anyway... ). Debian may be more unix-like as well but I've only had limited experiece with it.

Funny, I consider Slackware the least Unix like. Maybe where the store things is a bit more like some others, but the init structure is completely screwed. Saying Linux is like Unix is very misleading. There is no "Unix". There is Solaris, HPUX, Irix, etc. In the same vein there is Slackware, RedHat, Debian, Mandrake, Suse, etc. They all provide a similar setup.

Then why not try FreeBSD?

Linux is a Unix OS.
There are a few standards for how a Unix OS will behave, like POSIX and SUS, and as far as I know Linux is as compiant as any commercial Unix.

Linux is most certainly a unix.

It's just not a very good one!

cRock wrote:

It's just not a very good one!

What makes you say that?

From what I've been hearing BSD is pure UNIX.

There really isn't any such thing as pure Unix anymore, there hasn't been for a long time. Unix is an idea and a philosophy on operating system design, and useful abstraction.

This is a good site that shows the pedigrees of various Unix operating systems.

This IEEE comitee defines POSIX

I believe these people define the Single Unix Specification, and may still own the Unix trademark

So whats the difference between BSD Unix and Linux like SuSe?

malebolgia wrote:

So whats the difference between BSD Unix and Linux like SuSe?

They are implemented in completely separate codebases but are both attempting to implement the same ideas. The kernel and system services may behave slightly differently from a programmers perspective. BSD systems most often use the BSD style init (init is the 'master process', usually PID 1 or 0 that controls system initializiation and daemon startup) and Linux more often uses SysV style init. BSD's seems to more often use ports, or have no software packaging system while most Linux distro's use RPM or dpkg to manage software.

The current BSD systems all have one team that works on the entire OS, kernel and userspace. Linux is a separate project that works only on the kernel; core libraries and system utilities come from other projects.

Saying Linux is like Unix is very misleading. There is no "Unix". There is Solaris, HPUX, Irix, etc. In the same vein there is Slackware, RedHat, Debian, Mandrake, Suse, etc. They all provide a similar setup.

At a time there was just Unix. Now, however, there are tons of variants of unix and Linux is one such variant. However, there are many flavors of linux and while they all use the same kernels, they try to be unix like in different ways....

The whole idea of GNU is to distribute a free unix -- and that's just what linux is.

It's just not a very good one!
...
What makes you say that?

He's probably used other variants of unix like solaris and therefore knows what "good unix" is like =)

Well said sroylance.

Linux is not UNIX®.
FreeBSD is not UNIX®.
OSX is not UNIX®.

AIX, HP-UX, IRIX, SCO OpenServer, Solaris and UNIXware are all UNIX® systems.

The Open Group owns the UNIX® brand, and has the sole right to say what is UNIX®. POSIX is a set of standards that don't themselves define UNIX®. BSD, the Berkeley System Distribution, is defunct. There hasn't been a BSD for nearly a decade. FreeBSD, OpenBSD etc. are all descendants of 4.4BSD-Lite, which is a legacy of the BSD project that is not itself UNIX®. Corruptions of "UNIX", like "Unix" or "unix" may have specific meanings to individuals, but don't have any official meaning.

Q. Is Linux really like Unix?
A. Yes. Linux works like UNIX® does in many ways. It just isn't UNIX®.

Q. Is Linux a "Unix OS"?
A. Linux is not a recognized UNIX® system. "Unix OS" is an imprecise term that has no official meaning.

Q. Is BSD pure UNIX?
A. BSD UNIX is no longer available. But when it was, it did include genuine AT&T UNIX. To use BSD, you had to purchase a UNIX license from AT&T first. Since then, the UINX codebase and rights have changed hands several times. Currently the Open Group owns the rights, while Caldera owns the reference code. In that respect, Caldera's UNIXware product is the most pure UNIX® system, being directly descended from the last AT&T UNIX product. Getting back to the question, BSD wasn't "pure" UNIX because it was pure UNIX plus some proprietary extensions.

You should note that since AT&T divested, UNIX® systems don't come from the same codebase; conformance comes through testing instead. In other words, today anybody can develop a UNIX® system, whereas before it all came from AT&T. FreeBSD and other 4.4BSD-Lite derived projects include no UNIX® code or license. They came from the University of California, not AT&T. The U of C was never a producer of UNIX.

Q. Is "Unix" a generic term, like the famous Xerox case?
A. No, UNIX® is still a protected copyright. Using the term improperly ranges from being a personal faux pas to being outright fraud when the trademark is used without consent for monetary gain. In practical terms, it's a good way to distinguish between dilettante and professional. Because the UNIX paradigm is highly precise, you know that you don't want to give root access to a person who might accidentally issue a command like `rm -Rf /*'

Q. So whats the difference between BSD Unix and Linux like SuSe?
A. BSD UNIX was a custom UNIX distribution from the University of California at Berkeley. BSD UNIX started with real AT&T UNIX, and added certain proprietary features and utilities to it. S.u.S.E. is a Linux distribution that uses the Linux OS kernel, similar to how BSD was a distribution of the UNIX OS. But S.u.S.E. is not a UNIX® distribution, it's a Linux distribution. The difference is the software -- it's not the same. Although some aspect resemble each other, they're actually quite different.

Time for some humor:

And I can say for certain Linux is not Eunuchs.

Speed: Nice reply.

Thanks DiMaestro! I've put a lot of hours into researching UNIX and its progeny. It's a fascinating story that deserves to be told, and told accurately. Isn't it ironic that the most powerful and versatile OS of all time was originally considered to be castrated in comparison to MULTICS?