バージョン：25.2

diskSpace

function
The diskSpace() function returns the amount of free space on the disk where the specified file or directory is located. If no parameter is given, it returns the amount of free space on the disk where the current directory is located.

         if the diskSpace is less than 5 MB then put "5 MB warning"
        put diskSpace("/Volumes/st508") into bytesAvailable

As of version 1.69, the diskSpace function returns a value with unit type “bytes”, for easy conversion to other diskSize types (MB, GB, etc.).