It specifies a directory or a list of directories in which to search for the MySQL library. If the value is a directory pathname specifier then it is passed to directory. If the value is a list of directory pathname specifiers then each item is passed to directory. The collected results are the list of directories to search in.
Note that this default will match any MySQL release, so if you need to be sure to match a specific MySQL release, you need to change the value of
such that it matches only that particular release.