Substitution with sed + bash function

you can use the "e" option in sed command like this:

cat t.sh

myecho() {
        echo ">>hello,$1<<"
}
export -f myecho
sed -e "s/.*/myecho &/e" <<END
ni
END

you can see the result without "e":

cat t.sh

myecho() {
        echo ">>hello,$1<<"
}
export -f myecho
sed -e "s/.*/myecho &/" <<END
ni
END