bash grep can return an empty space, how to substitute the empty space for a string?

Question

I am attempting to grep an inbox for survey results, in which the subject will include the answer to the following question: "The answer to your question is ___"

The answered question will take the form of: "Subject: RE: The answer to your question is yes|no|' '"

I have tries the following in a bash script:

subject=$(cat /var/mail/incoming | grep '^Subject:' | cut  -d' ' -f 9)

I am expecting output similar to the following:

yes
no
no
yes

yes
no

In which there will be spaces where a non-answer occurred, and this is exactly what I see when I grep at the command line.

However, when I store the results in a var, the output is:

yes
no
no
yes
yes
no

How do I detect a space at the end of my grep command and replace it with "none"?

Desired output:

yes
no
no
yes
none
yes
no 

Answer 1

subject=$( awk '/^Subject:/ { print ($9 ? $9 : "none") }' /var/mail/incoming )

For example:

$ cat file
Subject: RE: The answer to your question is yes
Subject: RE: The answer to your question is no
Subject: RE: The answer to your question is no
Subject: RE: The answer to your question is yes
Subject: RE: The answer to your question is
Subject: RE: The answer to your question is yes
Subject: RE: The answer to your question is no

$ subject=$( awk '/^Subject:/ { print ($9 ? $9 : "none") }' file )

$ echo "$subject"
yes
no
no
yes
none
yes
no