We do have some rules here and we expect everyone to follow them. One of the rules is:
(6) Do not post classroom or homework problems.
If you suspect that a question violates this rule, please don't answer it anyway. This encourages further rule violations.
At this point passat, if he waited for years, knows how to download the source code for a shell. I guess what he wanted, but that's not the same thing as creating the source code for a shell.
Answering a 4 year old question is a bit odd, but I guess I'll leave the thread open.