Photoshop won't recognize files unless they have file extension

On those files, try Control-clicking on them, Open With, and then mouse over to Photoshop.

Also try this Automator action.

Try resetting the Launch Services database. Download OnyX. Launch the utility and click on the Maintenance heading, then the Rebuild tab. Turn on the check box for LaunchServices and click Execute at the lower right. Restart the Mac to allow it to rebuild the database.

I just did a little testing here to try and duplicate your issue. You're right. I pulled various old files from my archives that were created under OS 9. Which as you know, didn't normally use any type of file extensions.

Anything that was a TIFF, JPEG or EPS file opened in Preview, even though I know they were created in Photoshop. Adding the appropriate extension didn't change anything, they still opened in Preview. The only ones that opened in Photoshop when double clicked were those saved as native Photoshop files, even though they didn't have a .psd extension.

I was able though to do the normal process of doing a Get Info on a TIFF, changing it to open in Photoshop and then clicking the Change All button. From then on, all TIFFs opened in Photoshop as expected whether they had an extension or not.

My files without extensions are "appearing" as Terminal files...

That means that not only do they not have an extension, but they've somehow also lost their Type and Creator codes. Adding an extension gives something for OS X to work with, but otherwise has no clue what to do with them. They're essentially considered unmarked.

To save yourself some headaches (and a LOT of time if you have hundreds of such files) try a renaming utility. There are several to choose from here. You can use it to add, for example, a .tif extension to all of your TIFF images.

Oh yeah...creator codes were permanently removed from Snow Leopard. So files like that won't work anymore. It normally isn't an issue, except that Adobe is hesitant to adopt the latest Apple technologies.

Oh yeah...creator codes were permanently removed from Snow Leopard. So files like that won't work anymore.

More or less. OS X itself doesn't use them anymore, but it still does recognize them when there is no extension to go by. Such as older Type 1 fonts. In my example, the old TIFFs I pulled off disk to test. The OS recognized they were a TIFF and opened them in Preview. The only mistake being they had Adobe's creator code of 8*** and they opened in Preview anyway. But assigning all such TIFFs to Photoshop corrected that easily.