How to globally replace strings in lines NOT starting with a certain pattern

Question

I want to globally replace the string foo with the string bar, using sed. This should only be done for lines which do NOT start with the string ##Input.

I can\'t get

Answer 1

You got to escape # as in \#.

Answer 2

An ugly answer for an ugly request (i.e. they get what they asked for):

echo \{
for file in *.json; do
    sed -n '/^[\{\}]/! s/\([^\,]\)$/\1,/; /^[\{\}]/!p' $file
done
echo \{

Answer 3

You just need to negate the match using !:

sed -i '/^##Input/! s/foo/bar/g' myfile