How do I use floating-point division in bash?

bash floating-point arithmetic-expressions
Medya Gh picture Medya Gh · Oct 4, 2012 · Viewed 333.9k times · Source

I am trying to divide two image widths in a Bash script, but bash gives me 0 as the result:

RESULT=$(($IMG_WIDTH/$IMG2_WIDTH))

I did study the Bash guide and I know I should use bc, in all examples in internet they use bc. In echo I tried to put the same thing in my SCALE but it didn't work.

Here is the example I found in the tutorials:

echo "scale=2; ${userinput}" | bc

How can I get Bash to give me a float like 0.5?

Answer

Ignacio Vazquez-Abrams picture Ignacio Vazquez-Abrams · Oct 4, 2012

You can't. bash only does integers; you must delegate to a tool such as bc.

Related questions

How to compare two floating point numbers in Bash?

I am trying hard to compare two floating point numbers within a bash script. I have to variables, e.g. let num1=3.17648e-22 let num2=1.5 Now, I just want do a simple comparison of these two numbers: st=`echo "$num1 &…

Read More
How to use expr on float?

I know it's really stupid question, but I don't know how to do this in bash: 20 / 30 * 100 It should be 66.67 but expr is saying 0, because it doesn't support float. What command in Linux can replace expr and do this equalation?

Read More
Arithmetic expressions in Bash?

I had used several ways to do some simple integer arithmetic in BASH (3.2). But I can't figure out the best (preferred) way to do it. result=`expr 1 + 2` result=$(( 1 + 2 )) let "result = 1 + 2" What are the fundamental differences between those expressions? Is there …

Read More