Bash and awk to do division

Question

I am trying to do a simple division computation between two integers that will result in a float. I do not want to use bc. This approach works for me for a different purpose with slightly different syntax but I am not quite sure where I am messing up. I am positive that the variables are getting assigned correctly, but I have an error once I try to do the division, and nothing actually gets assigned to the variable. Can anyone help?

Thanks in advance!

rate=`awk '{ shared = "'"${tempRatioArray[0]}"'"; total = "'"${tempRatioArray[1]}"'";\ printf "%3.0f\t", shared/total }' | awk '{print}'`

Why don't you want to use 'bc' given that it seems quite suitable ? — Brian Agnew
– Brian Agnew, Commented Jul 9, 2014 at 16:29
I need to be consistent-- this is code that I am using for my thesis and I am on the tail end!! We had issues previously with bc properly handling variables so our workaround was awk and so far it has been working as expected! — c alvarado
– c alvarado, Commented Jul 9, 2014 at 17:01
Perhaps this is usefull: stackoverflow.com/a/24431665/3776858 — Cyrus
– Cyrus, Commented Jul 9, 2014 at 17:26

Tiago Lopo · Accepted Answer · 2014-07-09 16:32:47Z

You can use bc:

bc -l <<<"scale=3; 5/2" 2.500

Adapting to your code:

bc -l <<< "scale=3; ${tempRatioArray[0]} / ${tempRatioArray[1]}"

anubhava · Accepted Answer · 2014-07-09 16:56:45Z

2

That is not correct way of using shell variables in awk and you don't need 2 awk commands.

Use it like this:

rate=$(awk -v shared="${tempRatioArray[0]}" -v total="${tempRatioArray[1]}" 'BEGIN { printf "%.3f", (shared/total) }')

edited Jul 9, 2014 at 16:56

answered Jul 9, 2014 at 16:28

anubhava

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4 Comments

c alvarado Over a year ago

Thank you for the response! I have tried this: rate=awk -v shared="${tempRatioArray[0]}" -v total="${tempRatioArray[1]}" 'BEGIN { printf "%3.0f\t", (shared/total) }'`` but the rate comes out to equal 0...

anubhava Over a year ago

Can you run:

awk -v shared="${tempRatioArray[0]}" -v total=${tempRatioArray[1]}" 'BEGIN { printf "[%s][%s]%3.0f\n", shared, total, (shared/total) }'

and tell me its output.

c alvarado Over a year ago

The output is this:

val for LLC ratio: 5100566 75873367 rate = [5100566][75873367]3.0f ./LLC_resource_migrate.sh: line 204: [: [5100566][75873367]3.0f: integer expression expected

anubhava Over a year ago

Great to know, can you mark the answer as accepted by clicking on tick mark on top-left of my answer.

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