what is under my OS ?

[omr_a]

Hello

As I understand the windows or linux os is an interface which relates the user with the shell(Dos,bash...etc) which in turn communicate with the computer HW-through other layers of lower level- to perform the operations..is that right ?

then whats under windows is DOS ? I mean if I bought a computer with no OS I will found DOS ? and what about cmd.exe, is it DOS or some other shell ?

I know that GNU Linux works with a bash shell right ? so if installed Linux on a computer the bash shell will replace the DOS ?

sorry for my long topic I just want to understand this issue simply

thank you

 

[Fear No Evil]

A computer with no OS doesn't have any DOS or shell program installed on it. Ultimately you should think of the BIOS as the 'base' OS. The BIOS is what allows the Operating System (DOS, Windows, Linux, MacOS) to load and run. DOS used to be the 'base' for windows but that is not the case anymore.

Linux is a bit different, you can have multiple 'shells' running in Linux. The shell is just a tool to manipulate the OS and a user can run one (bash) or multiple ones and switch between them (ksh, csh, etc.) The GUI of a Linux box does overlay the base OS, but the shell is not really the OS in the way DOS was to older versions of windows. A GUI is optional in Linux, and there are multiple GUI's people can run as well.

I'm sure others can explain it better but I tried.. 🙂

 

[omr_a]

thanks 🙂 I got it now (y)

 

[sourceninja]

In a nut shell (and overly simplistic)

The computer get's power, bios boots, the bios then loads the boots sectors of the the drives. (using linux as an example). This loads a bootloader such as GRUB. Grub then loads the system kernel into memory.

This kernel is the 'core' of the operating system. Once it is up and running all that other stuff really is inconsequential. It controls low-level processes, how memory is read and written, the order in which processes are executed, and how information is received and sent by devices like the monitor, keyboards, mice, and networks.

Once the kernel is loaded the kernel loads the 'user-space' (Init). This is the applications that make up your operating system. In the case of linux init will load a ton of important stuff including your shell (a GUI or text based interface to your computer). Once this is finished you have an operating system.

 

[Modelworks]

After boot the kernel unloads the bios and controls all the functions. The kernel is essentially windows or linux or MacOS. What you see as menus, text are a layer on top of the kernel. When you click something it goes driver -gui-kernel-cpu

 

[omr_a]

Thanks alot all of you for your Help 🙂
I was really confused , now I understand what goes under

 

[Nothinman]

If you really want to understand how an OS works you should get a copy of Understanding the Linux kernel or Inside Windows and read them.