03-08-2013 01:12 AM
Sounds like a trick question, or maybe related to something that is specific to your site. Maybe the answer is "Create the users in a central NIS or LDAP directory that has already been configured."
If there is no NIS, LDAP or similar central user information facility already set up, there is no way to create the users without logging in to each server at least once.
Or maybe you have some central management software that can run scripts in all 20 servers in an automated fashion? In that case, you should create a script that creates the users and sets their passwords, then have the management software do the work of sending the script to each server and running it. Then, "you" will not technically be logging to each server, but the management software will be doing something very similar under your control.
(Security note: if you do this, you should create the password hashes in one system and only add the pre-generated password hashes to your script. Never put plaintext passwords in scripts if you can avoid it.)