User admin configuration question

[Kris D. <kd...@we...>]

I found this quite easily shortly after I installed Webmin for the first
time...  and I soon decided it wasn't needed.  Now I need this:

In the configuration options for the user admin module, there is a space
to enter a command or series of commands to be run on adding a new user.
There is a way to indicate the username of the user you are adding via a
variable of some kind, but everything I've tried comes up blank.  No
error messages, just no action.

Any suggestions?  I know it can be done, I've done it before... and
promptly forgot to document it for myself.

-Kris