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Lock, Unlock Statements
Controls access by other processes to all or part of a file opened using the
Open statement.
Lock (channel, start, finish)
. . .
Unlock (channel, start, finish)
Arguments
- channel
- Required. Any valid .
- start
- Optional. Number of the first record or byte to lock or unlock.
- finish
- Optional. Number of the last record or byte to lock or unlock.
Remarks
The Lock and Unlock statements are used in environments where several processes might need access to the same file.
Lock and Unlock statements are always used in pairs. The arguments to Lock and Unlock must match exactly.
If the start and finish are not supplied, the lock will be for the entire file. If the start is specified but not the finish, the single record will be locked/unlocked.
If the file has been opened for sequential input or output, Lock and Unlock affect the entire file, regardless of the range specified by start and end.See Also
Example
Open Statement