FUNCTION SFIL_LOCK()

  Short:
  ------
  SFIL_LOCK() Attempts to lock a file

  Returns:
  --------
  <lSuccess> success

  Syntax:
  -------
  SFIL_LOCK(nTries,lInteract,[cMoreMessage])

  Description:
  ------------
  Attempts to lock entire DBF file. Tries <nTries>
  times and then allows user to retry or not <lInteract> by giving
  message [cMoreMessage] and asking YES/NO.

  Examples:
  ---------
   IF SFIL_LOCK(5,.F.)
       count for "S"$LNAME
       UNLOCK
   ELSE
       LOOP
   ENDIF

  Source:
  -------
  S_SFILOK.PRG