> Perhaps you know why ?
> Tell me please or give the link which can explan it.

Please have a look here: http://www.linfo.org/vmlinuz.html

> 2 - When linux start the init process launch the default shell process and
> give the prompt. The others process as linux commands or users process are
> the forks of this first shell process ?
> Can you explan simply  this point or  give me the link which can help me
> please in the starting of linux.

Have a look here too: http://unix.stackexchange.com/questions/5518/what-is-the-difference-between-the-following-kernel-makefile-terms-vmlinux-vml

More reference material : https://en.wikipedia.org/wiki/Vmlinux

Thanks - Aruna