OSDev.org

Hi, I am a new member of this forum and I have little experience on OSs development. I would like to ask you, suggest me a simple, open source unix-like operating system to study its code. It is important for me to start up with something simple and short as far as its code is concerned.
Thanks in advance.

Obvious choices: Linux (although it's so big and complex you'd only want to study parts of it, and still you'd have to learn a lot to find those parts), and Minix (the original Unix like OS developed for students to study) and how Minix evolved to it's current form (Minix 3, IIRC), and the BSDs (also similiar situation as Linux, although I suspect them to be smaller and slightly more organized). Other than that, lots of OS projects aim to be POSIX compliant, you can gather bits and pieces from them, and even stuff from non POSIX OSs, since most of POSIX stuff are implemented anyway, with various degrees of "innovation" and "modification". Hope this helps,

JVFF

What do you mean by simple? If you mean like a 'Hello World' example than you could find one in the Wiki. If you mean something more complex than that, than the kernels mentioned above would be suitable.

I hope you don't get discouraged in your OS devving - welcome to the forum!

They say Plan 9 from Bell Labs would be great. I've been planning to confirm that someday.

There's UnixLite which is a small Unix clone written in C++, and has binary compatibility with Linux.

There is MortOS.. It's a neat project with a UNIX-like feel, It already has binutils ported (and running) natively, Along with pdksh/ncurses and lots of other goodies with a considerably Tiny kernel..

http://www.mort-os.com/

But quite a few OSDev projects out there offer a system with a "UNIX-like" feel, Should take a browse around to find one you like.

Linux kernel 0.01 is pretty small.

Well, first of all thank you for your anwers.
I think its minix the OS I will start up with studing since it is created for such purposes and it seems to be well documented ( I am talking about Tanebaum's book ). Actually I did my first post after reading this page where I realized that there are more OSs to study than I could imagine. Of course not all of them are proper for my needs but I saw lots of other candidate hobby- and university- OSs that could also be suitable for me.
Actually I was looking for something small, simple, and well-organized as far as its source code is concerned.

- karampin -

I'd go so far as to say that too many operating systems are Unix-like.

Crazed123 wrote:I'd go so far as to say that too many operating systems are Unix-like.

That sounds like something a windows user would say

There will never be enough Unix-like systems.

Brynet-Inc wrote:

Crazed123 wrote:I'd go so far as to say that too many operating systems are Unix-like.

That sounds like something a windows user would say

Or someone interested in OS research.

There will never be enough Unix-like systems.

On what basis do you say this, other than mind-numbing fanboyism? If you don't have anything intelligent to add, stop wasting everybody's time.


Back to the topic... Minix is a pretty good choice for understanding how things work at the implementation level, but remember that it is not a good example of OS design. No other microkernel OS I know has used the idea of architectural layers in such an arbitrary and performance-limiting way.

Colonel Kernel wrote: Back to the topic... Minix is a pretty good choice for understanding how things work at the implementation level, but remember that it is not a good example of OS design. No other microkernel OS I know has used the idea of architectural layers in such an arbitrary and performance-limiting way.

So what would you recommend me as second choice ? Maybe something more common and *orthodox* as far as it's design is concerned.
I hope, I am not becoming annoying asking in some sort the same question.
Thank you again.

- karampin -

Brynet-Inc wrote:That sounds like something a windows user would say

And that sounds like something a hopeless Unix fanbody who isn't quite ready for operating system design would say.

There will never be enough Unix-like systems.

Unix is a weak pun on Multics, or possibly the plural of "man without his genitalia".

But to speak seriously... Unix was designed 30 years ago as a stripped-down Multics that could run on a PDP-7. It spread like a virus because C made it portable, and later the open-source movement copied the only decent-and-free OS design available, letting it survive even longer. Now it keeps creaking out of sheer inertia.

Unix attempts to treat everything as files (except what it doesn't), has a coarse security model that concentrates too much power into one user account, keeps far too many abstractions in-kernel, requires a crock called sockets for network access, has no truly good IPC facilities, and imposes its damned worldview on every other operating system out there.

The day Glider (my OS) is ready for everyday use, I will remove Linux from my hard drive.