Hidden files

Image: Ujnotes — CC0 1.0

Show or hide Finder hidden files with defaults write and killall Finder, including the OS X 10.8 form.

Show or hide hidden files in Finder, then restart Finder.

Show hidden files

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

Hide hidden files

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

OS X 10.8 and prior

Show:

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

Hide:

defaults write com.apple.finder AppleShowAllFiles FALSE ; killall Finder