bash - in variable in heredoc

Question

Is there any way to for a Bash heredoc to interpret ' ' in a heredoc?

I have an iteratively built string in a loop, something like

for i in word1 word2 word3
do
        TMP_VAR=$i
        ret="$ret
$TMP_VAR"
done

and then I want to use the created string in a heredoc:

cat <<EOF > myfile
HEADER
==
$ret
==
TRAILER
EOF

however I would like to interpret the " " character as newline, so that the output is

HEADER
==
word1
word2
word3
==
TRAILER

instead of

HEADER
==

word1
word2
word3
==
TRAILER

Is it possible? Or should I perhaps build my initial string somehow otherwise?

Answer 1

In bash you can use $' ' to add a newline to a string:

ret="$ret"$'
'"$TMP_VAR"

You can also use += to append to a string:

ret+=$'
'"$TMP_VAR"