And not only this word as the necessary "lego pieces" as well.
In fist place, I must do a grep to the /etc/alias file to see if the user name already exists.
If nothing is returned then the name does not exist but if something is returned it might be that our "new user name" is either some that already exists (in which case it can't be accepted) or only a part of an already existing user name (in which case it can be accepted).
Both cases must be accounted for.
After the name has been validated, it can be used to build the new user's account and necessary data structures.
So, back to exist_user? right now...