Q: how to show hidden files for mountain lion

To show hidden files on OS X Mountain Lion, just open Terminal and copy:

defaults write com.apple.finder AppleShowAllFiles TRUE && killall Finder

When you want to hide hidden files again, just type the same command, but change TRUE with FALSE

This works. But all the hidden file icons are grayed out and unresponsive to clicking. I need to be able to get inside my User/Library folder to retrieve a Mail preference file from Time Machine. Is there another way to make hidden files fully visible and able to be interacted with?

iMac (21.5-inch Late 2012), OS X Mountain Lion (10.8.4)

Found a partial answer in another discussion here.

Enter the following in Terminal. It will prompt for the admin password.

sudo chflags nohidden ~/Library

After you do that, the Library folder will be fully visible and its contents available to be accessed.

Unfortunately, this does not apply to older Time Machine backups done when the Library folder was not visible.

iMac (21.5-inch Late 2012), OS X Mountain Lion (10.8.4)

There's also a nice little free menubar app you can download called DesktopUtility.  It allows for a quick way to toggle the visibility of hidden files and the user Library.  A lot quicker than using Terminal.

You can open the Library folder from the Finder by holding down the option key and selecting Library from the Go menu. Once you've done that, you can enter Time Machine and the Library folder will be open in Time Machine.

thank you!

The two terminal replies did exactly what I needed.