comparison of integer and floating point numbers in shell script

Question

In shell script how can we compare (integer and floating point) ,(flaoting point and floating point),(floating point and integer),(integer and integer) with only one if condition.

i have few examples like

 set X=3.1
  set Y=4.1
  if [ $X < $Y ] then
    echo "wassup"
  endif

But running the above from cron job doesnt seem to work.

Answer 1

The way to carry out floating point operations in bash is to use bc which is available on almost all linux distributions.

# bc will return 0 for false and 1 for true
if [ $(echo "23.3 > 7.3" | bc) -ne 0 ] 
then 
  echo "wassup"
fi

There's a good article available on linux journal about floating point math in bash using bc.