Have you ever done some house cleaning, moving a ton of files to the trash, and then wanted to check a few of the files “one last time” before emptying the trash for good? It’d be nice if you could just double-click on a file in the trash to check it, but alas, it’s not to be. When you try that, OS X tells you that the document couldn't be opened, because it is in the trash. But you already knew that.
So the usual method of doing this is to find the files you wish to check, drag them to the Desktop or other convenient spot, open them in their application of choice, and then (assuming they can be trashed) drag them back into the trash can. Here are a couple of workarounds that can save a bit of time in the review process.
The first trick is to use the File: Open menu in an application that can open the file in question. If you’d like to check some image files, for instance, use Preview. Within Preview, select File: Open, and once the dialog box appears, type Shift-Command-G, which brings down the Go to Folder entry box. Enter ~/.Trash as the path, and click Go. You’ll soon be looking at a list of all the files in the trash on your boot disk. Click one (or more, using the Shift and/or Command keys) file(s), click Open, and presto, Preview will show you each image file. You can use File: Save As to save any images you’d like to keep; if they’re all OK to delete from the trash, just close Preview when you’re done.
An even easier way of accomplishing the same result is to use the Dock. Open a Finder window showing the contents of the Trash by clicking on the trash can icon in the dock. Now just drag one or more files from the open trash window, and drop them on a docked application that can open that type of file. To force a docked application to accept the dragged file, you can hold down Command and Option prior to dropping the file, though this shouldn’t be necessary if it’s a file type that the application can handle.
Not the world’s most advanced tip, but it can save a bit of time and repetitive drag and drop actions when all you want to do is confirm that you really can delete something from the trash…