does anyone created its own shell using c?

Question

shell that suport internal comands like cd,echo,help,quit etc

Answer 1

Yes, lots of people have. If you want to see an example, look at the source for busybox.

Answer 2

It's not that hard, I actually made a simple one as a project for an operating systems class last fall that could run external programs and keep track of command history.

Answer 3

I did one for a programming class too, fortunately we didn't have to manage command history, but we did have to support any combinations of piping and redirection (that was a pain).