How to pass a bash variable into awk

Question

I have a variable that is created in bash, and want to use it within awk statement to create a file by concatenating it with a string for the filename.

awk -v value="${index}" 'BEGIN{}{print $9 >> "example_value.txt";}END{}'

How can I do this?

Answer 1

You have to use it outside of the double quotes. awk concatenates it without any other character:

awk -v value="${index}" 'BEGIN{}{print $9 >> "example_" value ".txt";}END{}'

Answer 2

You could use -v option as in the examples previously posted.

Or you could just use something like :

awk 'BEGIN{}{print $9 >> "example_'"$index"'.txt";}END{}'

Moreover, you don't have to use {} around the variable index in this case.