# Show keycodes used by Xorg
# start xev and show only the relevant parts:
xev | awk -F'[ )]+' '/^KeyPress/ { a[NR+2] } NR in a { printf "%-3s %s\n", $5, $8 }'

# Alternative approach to show keycodes, with standard AWK formatting.
awk '
	/^KeyPress/ {
		A[NR+2]
	}
	NR in A {
		B=substr($7, 0, length($7) - 2)
		printf("%3d %s\n", $4, B)
	}
' <(xev)