How Can I calculate the sum of a specific column using bash?

Question

I want to calculate the sum of a specific column using bash without using the print that specific column (I want to keep all the output columns of my pipeline and only sum one of them!)

Answer 1

If you wanted to sum over, say, the second column, but print all columns in some pipeline:

cat data | awk '{sum+=$2 ; print $0} END{print "sum=",sum}'

If the file data looks like:

1 2 3
4 5 6
7 8 9

Then the output would be:

1 2 3
4 5 6
7 8 9
sum= 15