passwd_duplicate_username

This built-in function ensures that each username in /etc/passwd is unique. It succeeds if that is the case and fails otherwise.

Duplicate user names in /etc/passwd create problems since it is unclear which account’s privileges are being used.

The adduser command will not let you create a duplicate username. Such a setup typically means that the system has been compromised, tools to handle user management are buggy or the /etc/passwd file was manually edited.

Delete duplicate usernames or modify them to be different.

Usage