Write data to the file.
This communicates with the Linux distribution through Bridge. While functionally similar to the SD library, the underlying code and connections are different.
- file: an instance of the File class (returned by FileIO.open())
- data: the byte, char, or string (char *) to write
- buf: an array of characters or bytes
- len: the number of elements in buf
byte : write() will return the number of bytes written, though reading that number is optional