You can write hybrid applications that can access Macintosh volumes
but retain a UNIX interface. To do this, you must use the calls provided in
the Toolbox. These calls are documented in "Inside Macintosh" with the
differences documented in the "A/UX Toolbox" manual.
Standard Macintosh applications can, of course, use both UNIX and Macintosh
file systems simply by making the standard Macintosh File Manager calls. If
these calls are used to access a UNIX file system, they are mapped internally
to the appropriate UNIX routines instead, without the Macintosh application
being aware of any differences.
On the other side, UNIX programs cannot see or use the Macintosh volumes. The
"ls" binary is a perfect example of this. Because it was written using the
standard UNIX libraries, it cannot access any Macintosh volumes. Because of
this, shell scripts are also incapable of accessing Macintosh volumes. It is
conceivable that you could write your own version of "ls" that uses the Toolbox
but retains the same interface as the existing command. At that point, you
could then use the command from within a shell script.
The A/UX Development Tools product is a full development package supporting
this type of development.