[TUHS] Ideas for a Unix paper I'm writing

[Nick Downing]

Greg, it is very interesting what you've said about the origin of file
descriptors... it might be worth looking into the history of this a
bit deeper, but from what you've said the earlier systems didn't have
the polymorphic file descriptors that unix has, from what I understand
of your post the device nodes in the filesystem were new with unix?  I
totally agree that the text format and the filesystem work together to
promote inter-operability and user `ownership' of their data (a recent
phenomenon along the same lines is XML so we might say that unix
predicts current trends by 20-25 years in this respect as well).
Another really important thing to mention is the Bourne shell, it's
kind of the glue that sticks it all together, and a bit of a
masterpiece in itself, being fraught with compromise but having
programmability and a batch capability without taking away from its
main purpose of being a useable interactive shell.
cheers, Nick

On Tue, Jun 28, 2011 at 2:13 PM, Greg 'groggy' Lehey <grog at lemis.com> wrote:
> On Tuesday, 28 June 2011 at 10:11:40 +1000, Warren Toomey wrote:
>>
>> I'm having some trouble thinking of the right way to explain what is
>> an elegant design at the OS/syscall level, so any inspirations/ideas
>> would be most welcome. I might highlight a couple of syscall groups:
>> open/close/read/write, and fork/exec/exit/wait.
>
> The system call interface is one thing, but I'm not sure it's the most
> important one.  Older operating systems (in my experience, IBM OS/360
> and UNIVAC Omega and OS 1100) had similar interfaces.  Omega also had
> the concept of integer file descriptors (including 0, 1 and 2
> preassigned).  All of these systems had open/close/read/write, for
> example.
>
> I came to UNIX relatively late, and my first impression wasn't
> favourable.  It took me a while to realise what the real advantages
> were.  For me, they're:
>
> - Text files.  At the time, any data of any importance was stored in
>  custom-designed file formats.  That was more efficient, both in
>  terms of processing time and space, but it made things difficult if
>  anything went wrong.
>
> - The file system itself.  I think the design of the file system,
>  especially the separation of names and the files themselves, but
>  also special files, is one of the most far-reaching designs I've
>  ever come across.  To this day, I haven't found anything that even
>  comes close.
>
> You might also get some ideas from
> http://en.wikipedia.org/wiki/Unix_philosophy
>
> Greg
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