On Mon, Mar 21, 2011 at 03:39:20AM -0000, Rob wrote:
> >From what I understand.
This sounds suspiciously like homework, but...
>
I've never seen it described quite that way. Even
>
> The bottom Layer (the "base" or the "root") is the guts of the operating system. Here are the system files a user never sees, and should never mess with. Here is where input/output is controlled, and how memory and disc access are managed. Nothing here pertains to the normal user. So all these files are locked down and require the highest access level to be able to modify.
This is basically kernel level stuff.
>
> An administrator will need access here to perform a system update, or add a new feature (second hard drive, new graphics card, whatever). Otherwise it is left alone , So this layer requires root access
>
Quite possibly, this is my lack of knowledge, but practically speaking,
huh???
There's kernel, that handles I/O and hardware. If there are changes, in
most cases, either the kernel will handle it, hopefully, by loading a
module, or it may require admin access to install firmware. As for a
second hard drive, yes, it would require admin privileges to do
something with it. A network card, in today's Linux world, probably
wouldn't, it would be automatically detected and anyone could use it.
> The middle layer is the file system and the applications/programs. Depending on the way the computer is used and the ability of the user, this layer and the upper layer may use the same access level or they may be split. Assuming the machine is fully compartmented, then a supervisor might have middle level access so he can add and remove programs and change permissions of shared file systems. But he is not a "guru" so he does not have "root" access.
>
While interesting, I see little use for this in the real world, and
mostly of value for a homework question or test. There is limited
access.
> The top layer is the user layer. In a locked down machine, the user can open and run programs they are set up for them, store data where the supervisor has designated, and read files they have permissions for. Otherwise, they are locked out of the machine, and cannot change or view areas outside their boundaries.
>
> Why does windows not use the 3 layers like Linux ,Unix and Mac OS x?
It does. It may even do a better job when admins learn how to do it
properly. With group policy, different levels of users, and a point and
click that a) works as it's supposed to, and b) is (gasp) properly
documented, it's probably easier to provide granular access with Windows
than with Linux or OS X.
>
>
> And is all Linux have 3 layer system like Unix and Mac OS X
Just about all distributions have the same general principles, but then
there are things like puppy, meant to run from a USB stick, that just
gives any user root access, Fedora, which figures that passwords are a
waste of time, and, if you use the GUI package updater, allows any user
to update a signed package, and so on. Generally though, there is
kernel which meets hardware, and usually requires programming knowledge
to fix--then there are kernel modules and device drivers, which don't
require programming knowledge, but will require administrative access,
in Windows as well as Unix like systems.
Then, there are, as you say, middle level things, but in Linux, it's
probably more difficult to restrict access to some and allow to others
than it is with Windows, (with MS' power user group). These days
though, as Linux gets more like Windows, they have audio groups, video
groups, and all sorts of groups.
By the way if this is homework, I wouldn't use the answer I've given
you, which is from a curmudgeonly person who feels that Linux,
especially with most distributions, is just becoming worse all the time,
spending lots of effort in solutions in search of problems, rather than
fixing the things that should be fixed.
--
Scott Robbins
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