The reason why isn't clear - though it appears that some programs don't distinguish between CAPITAL and lowercase usernames. As such there lies a potential for conflict if you have a Marco and a marco account.
There currently doesn't appear to be any way to have this done via the
users-admin or Ubiquity - likely that these rules are hard-coded instead of pulled from the
You add the user via the command-line if you force a "bad username":
root@mine:~# adduser --force-badname Marco
Allowing use of questionable username.
Adding user `Marco' ...
Adding new group `Marco' (1002) ...
Adding new user `Marco' (1002) with group `Marco' ...
Creating home directory `/home/Marco' ...
Copying files from `/etc/skel' ...
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for Marco
Enter the new value, or press ENTER for the default
Full Name : Marco Ceppi
Room Number :
Work Phone :
Home Phone :
Is the information correct? [Y/n] y
If you want to add users without needing to
--force-badname you can change this line in
This will allow Uppercase names for users. While there is no way to add users to additional groups via the
adduser command you can use the
usermod command instead:
usermod -G admin Marco