left-alt

daniel@timecube:~/misc$ p left.txt
kb mode was UNICODE
[ if you are trying this under X, it might not work
since the X server is also reading /dev/console ]

press any key (program terminates 10s after last keypress)...
keycode  28 release # Enter key
keycode  56 press   # Alt key
keycode  42 press   # Left shift
keycode  42 press
keycode  42 press
keycode  42 press
keycode  43 press   # Backslash
keycode  56 release
keycode  42 release
keycode  43 release