During the transition from Mac OS 9 to Mac OS X, the way custom icons are stored on disks changed. We’ll quickly explain what happened and give you some tips to work around the issues.
Disks (or in the language of Unix, “volumes”) in Mac OS X have a special file called ”.VolumeIcon.icns” at the root level of the disk. You can see this in a Terminal window by using the commands:
% cd /Volume/DISKNAME
% ls -la
where DISKNAME is the name of a disk with a custom icon attached.
On Mac OS 9, the disk uses the same mechanism as a folder; a hidden file named “Icon\r” at the root level of the disk contains the custom icon. You can see this from a Terminal using the same commands as above. The only difference is that the file will be displayed as “Icon?”. The question mark is displayed because the OS doesn’t know how to display the carriage return in the file name (represented by ”\r”.)
So, you have a situation where the two versions of the Mac OS are looking for different files. If you’re trying to make a disk that mounts correctly on both, you’ll need to supply both files.
Let’s assume that you’re working with a folder that you’ll eventually use with Toast or some other disk creation tool (we’ll refer to this folder as a “project folder” in the following instructions.)
You can quickly create the “Icon\r” file required by Mac OS 9 using the standard copy and paste technique with Get Info on your project folder. You can use the Terminal to verify that “Icon?” is displayed in the folder.
Creating the ”.VolumeIcon.icns” file is a bit trickier. The reason is because Unix (and the Finder) doesn’t want to display a file with a period as the first character in the name. Any attempt to rename a file with a period at the beginning will cause the Finder to display a warning dialog. This means you’ll have to work at a Terminal prompt.
The following step-by-step instructions will help you out. The “project folder” referred to below is the folder where you are storing the contents of the disk you are creating:
Because the filename contains a period, you won’t see the results of your efforts in the Finder. However, after you burn the contents of the project folder onto a CD-ROM, you should see the icon show up on the desktop for both Mac OS 9 and Mac OS X.
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