id++ id-- : variable post-increment and post-decrement
echo $((a++))
++id --id
variable pre-increment and pre-decrement
echo $((++a))
- + unary minus and plus
! ~ logical and bitwise negation
** exponentiation
* / % multiplication, division, remainder
+ - addition, subtraction
<= >= < > comparison
== != equality and inequality
&& logical AND
|| logical OR