Well as the old saying goes, give a man a fish and he can feed himself for a day, teach a man to fish and he can get rich selling fish to other suckers (or something of the sort). So it is that Apple has given us the tools in Snow Leopard to fend for ourselves. Once again, Automator, Services, a custom keyboard shortcut and the good old bash Terminal are all we need to get the job done. Read on for the step by step instructions on how to make “Shift+Command+. (period)” toggle the display of hidden files in Finder.

Choosing a template for your Automator workflow

1. Open Automator (in your Applications folder) and choose Service from the list of templates provided and click the Choose button.
2. In the left hand column under Library, select Utilities.
3. In the second column, drag “Run Shell Script” to the right hand pane.
4. At the top of the right hand pane where you dragged the Run Shell Script action, click on the right-hand popup menu and change “any application” to “Finder”. This sets the service so it only appears and can be activated by the keyboard shortcut when Finder is the active application.
5. Then click on the popup menu next to “Service receives” and choose “no input”. It’s important you do this step after step 4 because if you do the reverse, Finder won’t be available as an option in the right hand menu.
6. Copy and paste the following text into the empty text area of the Run Shell Script action:

osascript -e 'tell application "Finder" to quit'
SHOWHIDDEN=`defaults read com.apple.finder AppleShowAllFiles`
if [ $SHOWHIDDEN -eq 1 ]; then
defaults write com.apple.finder AppleShowAllFiles -bool FALSE
else
defaults write com.apple.finder AppleShowAllFiles -bool TRUE
fi
osascript -e 'tell application "Finder" to activate'




Completed Automator action, ready to save (click to enlarge)

7. Choose File–>Save, and give the new service a meaningful name like “Toggle Hidden Files” that will appear in the Services menu. Once you’ve done that, you can go to the Services menu (located in the current application menu, next to the Apple menu) and your newly created service should appear there. You can even run it, it’s already fuctional, just lacking a keyboard shortcut.
8. Open System Preferences–>Keyboard–>Keyboard Shortcuts and select Services in the left column.


Setting the keyboard shortcut (click to enlarge)

9. Scroll down to the bottom and under the General category, you should see your newly created service listed there. Select it, then Double-click close to the right side of the selected line to reveal a field where you can enter a custom keyboard shortcut. Enter “Shift+Command+.” (might as well keep it consistent with the shortcut used in open/save dialog boxes), and then quit System Preferences.

That’s all there is to it. The really nice thing is built-in keyboard shortcuts override custom ones, so pressing “Shift+Command+. (period)” in an open/save dialog will not execute this service.

Finder Busy Error (click to enlarge)

Service Execution Error (click to enlarge)

Since the Finder will be restarted cleanly (using an AppleScript call to request it to quit), any tasks it is currently executing such as a copy operation, emptying the trash, etc. will prevent Finder from quitting and pop up the two error messages displayed on the right, without any modification to Finder’s preference plist file. If this happens, simply click “OK” to clear the two messages, wait for the Finder operation to complete (or cancel it) and try again.

I’ll reiterate how dumb it is that we have to implement this ourselves, but this oversight seems completely insignificant when we consider that instead of implementing a single keyboard shortcut that less than 1% of users will ever use, Apple have given all users a powerful and easy to use set of tools to add a keyboard shortcut for almost anything they could ever want to accomplish with one. Now go fish!

I also added two extra lines at the end of the shells script to improve usabiliy. Previously, after the action was executed, Finder would in most cases not end up being the frontmost application anymore since upon quitting Finder, the next application that is running would now become frontmost. The added two lines simply add a quarter second pause so Finder has a chance to relaunch before running the open command which brings Finder back to the front if it isn’t already.

I also changed the execution order a little bit so that the Finder is quit first before the plist modification takes place. That way if the Finder can’t be quit because it’s busy, no change will take place. This will prevent the state of hidden file display from unexpectedly changing between reboots or logouts if you unsuccessfully executed the service and Finder couldn’t be quit.