How shell->Kernel communication happens?

[C.Krishna Prakash]

Hi,

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

Thanks in advance...

[A. Clay Stephenson]

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.

[dirk dierickx]

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

[Peter Godron]

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

Please also read:
http://forums1.itrc.hp.com/service/forums/helptips.do?#33 on how to reward any useful answers given to your questions.

So far you have not awarded any points to any answer (0 of 10) !

[Dennis Handly]

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

Or use tusc to see the system calls.