Floating Point Comparison in Shell Script

Question

Hello,

Can you please suggest me the syntax for doing floating point comparison in shell script. I am using bash.

I would ideally like to use as part of if statement

here is a small code snippet :

key1="12.3" result="12.2"

 if (( $result <= $key1 ))
    then
# some code here
fi

thanks

Kiran

Answer 1

bash doesn't do floats, use awk

key1=12.3
result=12.5
var=$(awk 'BEGIN{exit "'$key1'"<"'$result'"}')    
# or var=$(awk -vkey="$key1" -vresult="$result" 'BEGIN{print result<key?1:0}')
# or var=$(awk 'BEGIN{print "'$result'"<"'$key1'"?1:0}')
# or 
if [ "$var" -eq 1 ];then
  echo "do something"
else
  echo "result more than key"
fi

there are other shells that can do floats, like zsh or ksh, you might like to try using them as well

Answer 2

bc is your friend:

key1="12.3"
result="12.2"
if [ $(bc <<< "$result <= $key1") -eq 1 ]
    then
    # some code here
fi

Note the somewhat obscure here string (<<<) notation, as a nice alternative to echo "$result <= $key1" | bc.

Also, the un-bash-like bc prints 1 for true and 0 for false.