#!/bin/bash
s='LoadPlugin "olsrd_httpinfo.so.0.1" {
  # defaults to 1978
  #PlParam "Port"   "8080"
  # if you dont set these, the default is to listen only on the loopback device
  #PlParam "Host"   "80.23.53.22"
  #PlParam "Net"    "10.0.0.0 255.0.0.0"
  #PlParam "Net"     "0.0.0.0 0.0.0.0"
  #PlParam "Host"   "127.0.0.1"
}

LoadPlugin "olsrd_txtinfo.so.1.1" {
  #PlParam "port"   "2006"
  #PlParam  "accept" "0.0.0.0"
}

LoadPlugin "olsrd_jsoninfo.so.1.1" {
  #PlParam "port"   "9090"
  #PlParam  "accept" "0.0.0.0"
}'
MYPORT="1234"
sed '/^LoadPlugin.*olsrd_txtinfo/,/}/ s/^\([[:space:]]*\).*PlParam.*port.*/\1PlParam "port" "'"$MYPORT"'"/I' <<< "$s"