Replace content that have newlines using sed

Question

I have markdown README file that have html markers like this:

<!-- CONTRIBUTORS-START -->
<!-- CONTRIBUTORS-END -->

and I want to replace the text inside (it may already have stuff) with new content from a file that have html tags and newline characters (it's markdown table with html in cells).

I was trying to replace newlines by 0xFF do sed and after replace it back using this code:

CONTRIBUTORS=`./contributors -u jcubic -r jquery.terminal -m | tr '\n' $'\xFF'`
# contributors script get data from github and display markdown table
# or ERROR if rate limit reached

echo "$CONTRIBUTORS" | grep ERROR > /dev/null || cat README.in | tr '\n' $'\xFF' | \
    sed -e "s%\(<!-- CONTRIBUTORS-START -->\).*\(<!-- CONTRIBUTORS-END -->\)%\1\n${CONTRIBUTORS}\2%" #| tr $'\xFF' '\n'

but this don't work, how can I replace text inside markers with CONTRIBUTORS content?

It was kind of working when I use tr '\n' '\xFF' but it was replacing newline by x.

I found this article Sed: Mutli-Line Replacement Between Two Patterns and try it using:

sed -n "/CONTRIBUTORS-START/{p;:a;N;/CONTRIBUTORS-END/!ba;s%.*\n%${CONTRIBUTORS}\n%};p"

(I've replaced / by % in s command) but got error:

sed: -e expression #1, char 1630: unterminated `s' command

Answer 1

I've use this hack, I've simply converted new lines to smiley Unicode character "☺", while doing sed replacement, since newlines was causing problems.

CONTRIBUTORS=`./contributors -u jcubic -r jquery.terminal -m $@  | tr '\n' '☺'`

if echo "$CONTRIBUTORS" | grep ERROR > /dev/null; then
    echo "$CONTRIBUTORS" | tr '☺' '\n'
else
    cat README.in | sed -n "/CONTRIBUTORS-START/{p;:a;N;/CONTRIBUTORS-END/!ba;s%.*\n%${CONTRIBUTORS}%};p" | tr '☺' '\n' > README.tmp
    cp README.tmp README.in
    rm README.tmp
fi