Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

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UNLOCK releases locks applied to parts of a file.
 
UNLOCK [#]filenumber% [,{record& | [start&] TO end&}]
    ■ The argument record& can be any number between 1 and 2,147,483,647,
      inclusive, (equivalent to 2^31 -1). A record can be up to 32,767 bytes
      in length.
    ■ For binary-mode files, the arguments record&, start&, and end& represent
      the number of a byte relative to the beginning of the file. The first
      byte in a file is byte 1.
    ■ For random-access files, record&, start&, and end& are the number of a
      record relative to the beginning of the file. The first record is
      record 1.
 
Important
    ■ Be sure to remove all locks with an UNLOCK statement before closing
      a file or terminating your program. Failing to remove locks produces
      unpredictable results.
    ■ The arguments to LOCK and UNLOCK must match exactly.
    ■ Do not use LOCK and UNLOCK on devices or ISAM tables.