how to show hidden files in mac OS-X mountain lion

 

 To Make every hidden files visible

 

, lauch terminal and run this
defaults write com.apple.Finder AppleShowAllFiles YES
Press return

Now hold ‘alt’ on the keyboard and right click on the Finder icon
Click on Relaunch

reverse the operation by typing
defaults write com.apple.Finder AppleShowAllFiles NO

 

make one particular folder visible

If you want to make the Library visible then launch Terminal (in Utilities) and copy/paste the following line:

 

chflags nohidden ~/Library

 

The hit returned and relaunch the finder.

 

You can reverse this operation to hide it again using:

 

chflags hidden ~/Library