The user name, also called login name, allows users to access their own or a remote system.

Each user name must:

- be unique within a domain

- contain two to 32 letters, numerals, underscores (_), hyphens (-), and periods (.)

- begin with a letter

- have at least one lowercase letter

- not contain spaces

Note: When you change the user name in an NIS domain, it may take a while before the owner of the home directory is changed to reflect the new name.