topic Re: How shell->Kernel communication happens? in Operating System - HP-UX

How shell->Kernel communication happens?

C.Krishna Prakash — Mon, 29 Jan 2007 11:31:44 GMT

Hi,

Are(shell & kernel) they communicating thru machine langauge & how the communication happens....

Thanks in advance...

Re: How shell->Kernel communication happens?

A. Clay Stephenson — Mon, 29 Jan 2007 11:36:16 GMT

It happens quite well. And yes, ultimately it happens through machine language but essentially the answer to your question is "via system calls". All of the system calls are in section 2 of the man pages and they are the mechanism through which any application (including the shell) communicate with the kernel.

Re: How shell->Kernel communication happens?

dirk dierickx — Tue, 30 Jan 2007 02:17:25 GMT

most shells are also available in source code, so you can always check out the code from bash or others.

Re: How shell->Kernel communication happens?

Peter Godron — Tue, 30 Jan 2007 04:43:22 GMT

Hi,
imagine a set of boxes, stacked within each other, like a russian doll.

The innermost box equates to the actual hardware of the machine(CPU/memory etc).

The next box is the kernel, which controls access and maintains control of the hardware.

The next bigger box is the application, one of which is a group of programs called shells, other may be C programs, browsers etc.

So, for an application to 'talk' to the memory, it needs to address the kernel, which is done via system calls, which may be dressed up as C functions, such as strcpy.
The request from the application is translated into machine-code and, via the kernel, executed.

A brief, but technical, overview at:
http://en.wikipedia.org/wiki/Kernel_%28computer_science%29

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Re: How shell->Kernel communication happens?

Dennis Handly — Tue, 30 Jan 2007 05:07:56 GMT

>Dirk: so you can always check out the code from bash or others.

Or use tusc to see the system calls.