init and sched
 

After booting, GRUB gives control to the starting process.(my teacher told me).

the starting process may be init or shed. it depends upon implementation.

I know shed is the scheduler in unix. What does this shed do ????

I believe that GRUB (or any boot loader) gives control to the kernel. After the kernel has completed its initial startup, it passes control to a program such as init. Then init is responsible for getting the rest of the system set up.

If I understand correctly, any kernel has to have a scheduler function--is that the "sched" you are referring to?

In Linux, I believe the call to init is built into the kernel.

but in my pc shed has pid 0 and init has 1.

hence shed starts before init.