Re: [tlug] OT: Please educate me...

[David Santo Orcero <irbis@example.com>]

 Dear Rena: 

> Could you please explain the differences and similarities of Unix and
> Linux?

 Legaly or in techy-jargon?

 Legaly, Unix is a trademark of the Open Group. Unix trademark has been 
sold and bought lots of time, and has passed through lots of hand 'till 
our days. But I have said this only for legal purposed, to be conmited 
with the law, and blahblahblah.

 In our techy-jargon -alegal, but in its more common meaning-, Unix WAS an 
operating system. But years ago -sice the AT&T wars- is a  generic brand 
name -like cola- used to refer to the operating systems fully POSIX 
compliant, and that have some particularities. Some modern operating 
systems are called "flavours of Unix", because they are POSIX compilant, 
and have the same philosophy.

 As an example, AIX, Irix, Xenix, Solaris, Linux, Ultrix, HP-UX, SunOS, 
FreeBSD, OpenBSD, NetBSD, Coherent, BSD/OS, OSF1, Tru64 or Sinix -between 
others- are "flavours" of Unix. Think on Unix as "Cola", Linux as 
"Jolt cola", and Solaris as "Coca-cola".

 As far as the way to talk with the "core" of the operating system is 
similar, a program can be ported between flavours of Unix only recompiling 
it -converting it from its source code (human-readable) form to an 
executable form-. This is the cause of nearly all the flavours of Unix 
uses the same applications, the same graphical server architecture, and 
deep expertise and knowledge of one flavour of Unix can be recycled in 
another flavour of Unix.

 In fact, a deep understanding on more of a flavour of Unix assures that 
that person can adapt easily and quickly to another flavour of Unix.

 In common language: knowing Unix is like knowing how to drive cars. 
Knowing Linux is like diving Volvos or BMV: it does not matter that you 
have drived in the past a Ferrari or a Peugeot: you know how to drive 
cars, and in a couple of hours you are mastering Linux is you previously 
know other Linux flavour, as the same way as driving experience can be 
recicled when you change your car.

 The only mayor difference between flavours of Unix is the "branch". Some 
Unix are System V, and other ones are BSD. In the modern days, this can be 
read "the way to arrange the iniciatization files". But this is a 
configuration issue, and not a real flavour issue. As an example, SunOS 
comes with BSD inicialization scheme and Solaris with System V 
inicialization scheme, but a handy administrator can rearange the 
start-up scripts to do SunOS start-up on the way of System V, and Solaris 
start-up on the way of BSD.

 In the case of Linux, there are distributions branched as BSD, like 
Slackware, and distribution branched as System V, like RedHat, Mandrake or 
Debian. But nowadays the most of Linux distibutions are on the branch of 
System V.

 Yours:

David Santo Orcero
http://www.orcero.org/irbis