INHIBIT-LOGONS
Prevents all users, except the database owner (depending on option) and, on a UNIX system, the super-user, from logging on to the database.
Syntax
INHIBIT-LOGONS {(option}
Options
A prevents all users, including the database owner, from logging on. The UNIX super-user can still log on.
Restriction
SYSMAN and SYSPROG accounts only.
Comments
The database owner is the system user-id under which the database was created.
Note
If general users are allowed to logon under the database owner's system 
user-id, 
If INHIBIT-LOGONS (A  is executed, the only way the 
inhibit condition can be reversed is either by the super-user logging on to the 
database and using 
In the UNIX environment, disabling of logon is achieved by maintaining a 
LOCK.FILE file in the top UNIX directory containing the database.  A user must 
have UNIX read permission on this file to be able to log in. 
The lockdbase command performs the same function from the host system environment.