UniBasic Commands Reference - Rocket Software

LOCK
Syntax
LOCK resource.num {THEN statements [END] | ELSE statements [END]}
Description
The UniBasic LOCK command reserves a computer resource (such as a device or
file) for the current user process.
The lock is associated with resource.num, not the resource itself. Therefore, a
command that does not check for locks against the resource number will access the
resource even if it is locked. For example, an installation might assign locks 1
through 4 to four system printers. When an application needs to reserve printer 1, the
application executes LOCK 1. For lock effectiveness, all other applications must
check for locks before accessing the resource.
Resources are not automatically unlocked by the termination of the locking program.
The UniBasic UNLOCK or ECL QUIT commands must release them. Otherwise,
you can release resources by executing the ECL CLEAR.LOCKS command at
UniData level.
For more information about UniData locks, see Developing UniBasic Applications.
LOCK 1-425