% sh -c "kill `ps -caxwwopid,command | grep ScreenSaverEnginNotice the back tick before ps and after 1-6. This command is all on one line (though it's been shown here on two to narrow display width; remove the line break when entering the command).
| cut -b 1-6`;/usr/sbin/screencapture ~/Desktop/capture.pdf"
The screen saver will automatically start back up again.

