

Shift+Control+Eject: Will put your displays to sleep.Ctrl+Eject: Show the restart / sleep / shutdown dialog.If you are having trouble with a faulty Mac the following key combinations could be useful. (⌘+Y also works for single files, but in that case it’s less convenient.) Once that window is open, you can navigate between the files with the arrow keys in the upper left. You can also select multiple files to preview at once by holding down the Command key as you select them and then pressing ⌘+Y. (This also works with files on the desktop.) A full-page preview will pop up-and with Markup options, too. This works for everything from images and PDFs to Microsoft Excel files.

Click+Space Bar: If you want to see what a file looks like but you don’t want to waste time opening the associated app, select the file in a Finder folder and then press the space bar.
