More conveniently

This can be done more conveniently using Bash's numeric context:

if (( $(echo "$num1 > $num2" |bc -l) )); then  …fi

Explanation

Piping through the basic calculator command bc returns either 1 or 0.

The option -l is equivalent to --mathlib; it loads the standard math library.

Enclosing the whole expression between double parenthesis (( )) will translate these values to respectively true or false.

Please, ensure that the bc basic calculator package is installed.

Caveat: Exponential notation should be written as *10^; not E, nor e.

For example:

$ echo '1*10^3==1000" |bc1

Whereas

$ echo '1E3==1000" |bc0

Strategies to overcome this bc limitation are discussed here.

bash handles only integer mathsbut you can use bc command as follows:

$ num1=3.17648E-22$ num2=1.5$ echo $num1'>'$num2 | bc -l0$ echo $num2'>'$num1 | bc -l1

Note that exponent sign must be uppercase

It's better to use awk for non integer mathematics. You can use this bash utility function:

numCompare() {   awk -v n1="$1" -v n2="$2" 'BEGIN {printf "%s " (n1<n2?"<":">=") " %s\n", n1, n2}'}

And call it as:

numCompare 5.65 3.14e-225.65 >= 3.14e-22numCompare 5.65e-23 3.14e-225.65e-23 < 3.14e-22numCompare 3.145678 3.1456793.145678 < 3.145679