Wednesday 4 March 2015

Bash: bc command to round off a floating point number to an integer

Sometimes, we may need to round off a floating point integer in bash scripts.

Suppose in a bash script we may need to compare two numbers stored in two variable. One is a integer and other is a floating point number. Then, it is important that, we have to round off the floating point number before comparison,  otherwise we are always going to get error message.

A useful command to round off  floating point number is "bc"

Lets, see how bc command can help us. Everyone of us know that,  100/3 is 3.03030303030303..

So, let us assume that, in a scenario we may want only the number "3" to be stored in a variable.

Then the below method is useful:
[root@MANINMANOJ]#new=`echo '100/33' | bc`
[root@MANINMANOJ]#echo $new

Now, in another scenario we may want to have 5 digits after decimal point. Then, we have to use "scale" as below:
[root@MANINMANOJ]#new=`echo 'scale=5;100/33' | bc`
[root@MANINMANOJ]#echo $new

In above example five numbers after decimal point is considered in the output.

Kool :)

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