This is not part of the standard system, but there are cases
where it's useful to break out of the sandbox and access some
parts of the underlying host. Attached is a copy of an ilo for
unix with a host file system (hfs) device.

To use, a vocabulary will be needed. I've not yet placed this in
the blocks, but this little one can be used for now:

 0 (hfs) (host-file-system)

 2 :hfs:READ #0 ;
 3 :hfs:WRITE #1 ;
 4 :hfs:RDWR #2 ;

 6 :io:hfs (...n-) #900 io ;
 7 :hfs:open (sm-) [ &n:inc &fetch bi ] dip #0 io:hfs ;
 8 :hfs:close (-) #1 io:hfs ;
 9 :hfs:read-byte (-c) #2 io:hfs ;
10 :hfs:read-cell (-n) #3 io:hfs ;
11 :hfs:write-byte (c-) #4 io:hfs ;
12 :hfs:write-cell (n-) #5 io:hfs ;
13 :hfs:seek (n-) #6 io:hfs ;

A small sample:

  'README.txt hfs:READ hfs:open
  #1000 [ hfs:read-byte c:put ] times
  hfs:close

I'll probably have it added as a compile-time option in the
ilo-unix.c vm after further testing is completed, but it won't
be something that's enabled by default.