So i've been learning about shells
and i was wondering:
in dos (and whatever the shell in linux is called) are the commands (cd, makedir, del, pwd, etc) actually separate programs that are executed or are they just commands that are build in to the shell?
I'm mainly asking this because i'm thinking about trying to build my own shell and it would be nice if i could just copy the executables from dos, so i wouldn't have to implement it myself