Problems with AWK and power of (DD-WRT)

Question

I'm trying to extract the sum of numbers to a variable (cwr) in a file (wa_cidr) using this command:

cwr=$(grep -E "^([0-9]{1,3}\.){3}[0-9]{1,3}(\/([0-9]|[1-2][0-9]|3[0-2]))?$" /tmp/wa_cidr | awk -F '/' '`{n += 2**(32 - $NF)}` END {print n}')

However, the output is empty.

If I change the part...

{n += 2**(32 - $NF)} 

To...

{n += (32 - $NF)} 

I get a valid result written to the cwr variable.

It would seem that I cannot do the power of (32 - $NF) using either 2**X or 2^X in AWK.

If I do it on the command line, e.g. using...

$ echo $(2**5)

There's no problem and the result is 32.

I have tried many variations on the formula (parantheses etc.) but nothing seems to Work.

What is wrong? Can it be done in another way?

Thanks, Søren

Answer 1

If your regexp is correct then this would be the correct syntax to do what you appear to be trying to do:

cwr=$(awk -F'/' '/^([0-9]{1,3}\.){3}[0-9]{1,3}(\/([0-9]|[1-2][0-9]|3[0-2]))?$/{n += 2^(32 - $NF)} END {print n+0}' /tmp/wa_cidr)