var=2; let "var <<=2";echo $var   # tulostaa 8 -> 4*2

echo 0XOR0=$(( 0 ^ 0 ))
echo 0XOR1=$(( 0 ^ 1 ))
echo 1XOR0=$(( 1 ^ 0 ))
echo 1XOR1=$(( 1 ^ 1 ))

~	bitwise negation
<<	bitwise shifting (left)
>>	bitwise shifting (right)
&	bitwise AND -> echo $((0x1 & 0x6)) testaa onko toisen luvun bitti 1 asetettu
^	bitwise exclusive OR (XOR)
|	bitwise OR
