User names, also called login names, let users access their own systems and remote systems that have the appropriate access privileges. You must choose a user name for each user account that you create.
Consider establishing a standard way of assigning user names so that they are easier for you to track. Also, names should be easy for users to remember. A simple scheme when selecting a user name is to use the first name initial and first seven letters of the user's last name. For example, Ziggy Ignatz becomes zignatz. If this scheme results in duplicate names, you can use the first initial, middle initial, and the first six characters of the user's last name. For example, Ziggy Top Ignatz becomes ztignatz.
If this scheme still results in duplicate names, consider using the following scheme to create a user name:
The first initial, middle initial, first five characters of the user's last name
The number 1, or 2, or 3, and so on, until you have a unique name
For detailed guidelines on setting up user (login) names, see Guidelines for Using User Names, User IDs, and Group IDs.