Shell arithmetic

• expr only does integers:

 % expr 23 / 7
 3

• No problem, the GNU shell has a builtin arithmetic operator

• Which also does only integers:

 % echo $(( 23 / 7 ))
 3

• No problem, we can use bc:

 % echo 23 / 7 | bc -l
 3.28571428571428571428

• Ah, that's better.