Mason Loring Bliss <mason@acheron.middleboro.ma.us> typed:
:mkisofs requires a -o and a pathname. The usage when it's run without
:arguments lists the -o as optional. The man page lists it as being
:required. Running mkisofs without -o seems to dump stuff to the screen,
:and doesn't produce a file with an ISO filesystem in it.

dump stuff to the screen?  It dumps the ISO image to stdout.  You can
redirect that to a file and get a valid image.  Well, it seems to be
valid.  mkisofs diag tools are happy with it.

% mkisofs path > some.iso

The error is in the man page.  Though it's usage might be for suggested
usage so people don't complain when they forget to capture stdout.

Regards,
-- 
Geoff Wing   <gcw@pobox.com>            Mobile : (Australia) 0412 162 441
Work URL: http://www.primenet.com.au/   Ego URL: http://pobox.com/~gcw/