Using an here document variable in a while loop

Question

I am having trouble using a Here Document variable in a loop. Because this works

while IFS= read -r line; do
  echo "(${line})"
done <<EOF
one
two
three
EOF

But this doesn't

foo=<<EOF
one
two
three
EOF

while IFS= read -r line; do
  echo "(${line})"
done <<<"$foo"

Now I am a bit of a noob in bash scripting. Besides having question marks above my head I wonder how I can preserve the second syntax (the here document at the top of my script) and still make it work somehow.

Thanks for your help.

Answer 1

This doesn't set the variable foo to the contents of the heredoc:

foo=<<EOF
one
two
three
EOF

It's a variable assignment to an empty string, with a redirection. This might make it clearer what's happening:

foo=""  <<EOF
one
two
three
EOF

But you don't really need heredocs for this. Just do:

foo="one
two
three"

Answer 2

Apparently, you want to have an inline document variable and then split it on lines. You could do it like this:

lines=$(cat <<EOF
one two
three
four
EOF
)

IFS=$'\n'     # split on non-empty lines
set -o noglob # disable globbing as we only want the split part.

# use split+glob (leave ${lines} unquoted):
for line in ${lines}; do
   echo "${line}"
done

Note how I set the IFS to not split on line. The default would split on spc/tab/newline delimited words.