#!/bin/bash
s='next:
{
host = "http://n...content-available-to-author-only...e.com/err1.2.2/table/kenny.xml.gz"
};
second:
{
host = "http://n...content-available-to-author-only...e.com/err1.2.2/table/kenny.xml.gz"
};'
sed '/second:/{:a;n;/^ *host *=/!ba;s#"http://.*"#"next.com"#}' <<< "$s"
IyEvYmluL2Jhc2gKcz0nbmV4dDogCiAgICB7CiAgICAgaG9zdCA9ICJodHRwOi8vbi4uLmNvbnRlbnQtYXZhaWxhYmxlLXRvLWF1dGhvci1vbmx5Li4uZS5jb20vZXJyMS4yLjIvdGFibGUva2VubnkueG1sLmd6IgogICAgfTsKCnNlY29uZDoKICAgewogICAgIGhvc3QgPSAiaHR0cDovL24uLi5jb250ZW50LWF2YWlsYWJsZS10by1hdXRob3Itb25seS4uLmUuY29tL2VycjEuMi4yL3RhYmxlL2tlbm55LnhtbC5neiIKICAgIH07JwpzZWQgICcvc2Vjb25kOi97OmE7bjsvXiAqaG9zdCAqPS8hYmE7cyMiaHR0cDovLy4qIiMibmV4dC5jb20iI30nIDw8PCAiJHMi