sho/hide hidden files

defaults write com.apple.finder AppleShowAllFiles -boolean true ; killall Finder

or

defaults write com.apple.finder AppleShowAllFiles 1 &&  killall Finder

defaults write com.apple.finder AppleShowAllFiles -boolean false ; killall Finder

!!! this is not works!

defaults write com.apple.finder AppleShowAllFiles 0 &&  killall Finder