[Info-vax] What is a "real" Unix ?

[chrisq]

On 9/4/23 12:15, Simon Clubley wrote:
> On 2023-09-02, Bob Eager <news0009 at eager.cx> wrote:
>> On Sat, 02 Sep 2023 23:07:24 +0200, Johnny Billquist wrote:
>>
>>> On 2023-09-01 14:50, candycane wrote:
>>>>    SC> Yes, at least on Linux.
>>>>
>>>>    SC> The dd on other operating systems may use a different signal.
>>>>
>>>> Is dd on non unix systems?
>>>
>>> Yes. Linux for example. Linux is not Unix, but it certainly tries to
>>> work the same.
>>
>> "Jumped uo UNIX wannabe"
> 
> In that case, what is a "real" Unix ?
> 
> Is it something that implements a set of user-visible APIs and certain
> behaviour within its kernel (fork() semantics for example) ?
> 
> Is it something that came from a specific source code base and hence
> nothing else can never be called Unix no matter how compatible that other
> something is ?
> 
> If BSD is a Unix, then is System V also a Unix ?
> 
> If System V is a Unix, then why can't something else that also implements
> the same APIs and kernel behaviour also be a Unix ?
> 
> Or is Linux really a Unix after all (in every way that matters) and what's
> really going on here is just some out-of-touch BSD Unix elitism ?
> 
> Simon.
> 

To me, it's about design philosophy and implementation. Design
philosophy, where simple tools are combined to produce more
powerful tools. Layered design with properly defined interfaces
between the layers and powerful system library functions. Data
organisation at the byte stream level, with more advanced data
structures layered on top of that. All characteristics of unix
and unix like systems. Probably as lot more as well...

Chris