Unknown's existence in the application search path (ApplicationPaths) causes new icons to be defined for file types that don't have them. For example, it defines icons for the '.el', '.awk', etc. files in place of the default text document icon, however launching these documents still invokes the Edit application. The Unknown application also defines icons for the binary '.o', '.a', etc. files, but launching these does not invoke the text editor--instead these launch the Unknown application (just puts up an icon and quits--a no-op).
Unknown is not a no-op application when launched on entries that have (optional) Unix command entries in the Unknown.iconinfo file. The file name being launched is spliced into the Unix command and then it is executed by 'sh'. Before passing the command to 'sh', an alert box will verify with the user if Unknown should proceed. This verification can be turned off by doing 'dwrite Unknown Verify No'. If an error is detected, another alert box will report this fact and the exit code. This reporting can be turned off by doing 'dwrite Unknown ReportError No'.
INSTALLATION
To use the program, put the Unknown application in /LocalApps, or your personal ~/Apps directory, and then either use the 'View>Update Viewers' Workspace Manager menu item or logout and login again to see the new icons.
ADDING ICONS & MAPPINGS
To add your own icons and 'owner' application mappings, create an appropriate (48x48) tiff file whose name is the same as a file extension and add it to the /tiff subdirectory of the Unknown source directory. Then, edit the file Unknown.iconinfo and add an entry of the form 'extension:application:unix command<NL>'--the file contains several examples. The 'unix command' is optional and should have %s (up to five) where the file name being launched is to be substituted.
Then do:
make IconInfo # rebuild the IconInfo program
make files # generate the Makefile.preamble and Unknown.iconheader files
make # rebuild the Unknown application itself
make install # add the program to /LocalApps
make clean # clean up afterwards
Or do:
make complete # to do all the above
SUBMITTING ICONS
This is an evolving application. I hope the set of icons increases and improves (as others who are more artistically inclined get interested). Please send me Email if you have potential additions.
MISC
In theory, if one were to extract Macintosh icons and add them in as well and keep files on the NeXT (or any NFS mounted Unix host) via aufs using standard file extensions, one could view Macintosh directories from either the Macintosh or NeXT file browser (in icon mode) and see the same view. I don't plan to pursue this, however.
AUTHOR
Christopher Lane (lane@sumex-aim.stanford.edu) -- 1/25/91
