Because there is no need for users to edit the uidadmin file directly, there is little danger that the file will become cluttered with entries containing syntax errors; however, you should run a check on the file periodically and correct any problems that might exist. The uidadmin command provides options that allow an administrator to check the file, correct entries with syntax errors, and delete entries that map to unknown logins.
To check the consistency of the file, enter:
uidadmin -S scheme -c
where scheme is the name of the ID mapping scheme.
To correct the problems in the file, enter:
uidadmin -S scheme -f
When the -f option is entered, uidadmin gives you the opportunity to replace entries that contain syntax errors and to delete entries associated with logins that do not exist in /etc/passwd. It then sorts entries that are out of order.
Entering uidadmin with the -c option again will verify that all changes were done correctly.