Did you encounter a situation wherein you had to create several directories recursively? just use
mkdir/mkdirhier to do the trick

try this command:
$ mkdirhier {A,B,C}/{P,Q,R}/{X,Y,Z}
OR
$ mkdir -p {A,B,C}/{P,Q,R}/{X,Y,Z}
Output directory structure should be something like this. each dir A,B,C contains directories named P,Q,R which in turn contain dirs X,Y,Z.
Originally i was looking somewhere in
Exim4's documentation where in found out this info. normally this is used to create maildirs where they have several cur,new,tmp directories.