Only replace the first

src/freedombone

             sed -i "s|secret_key.*|secret_key : \"${SEARCH_ENGINE_SECRET_KEY}\"|g" ${SEARCH_ENGINE_PATH}/searx/searx/settings.yml
             if [ -f /var/lib/tor/hidden_service_searx/hostname ]; then
                 SEARCH_ENGINE_ONION_HOSTNAME=$(echo /var/lib/tor/hidden_service_searx/hostname)
-                sed -i "s|base_url.*|base_url : \"http://${SEARCH_ENGINE_ONION_HOSTNAME}\"|g" ${SEARCH_ENGINE_PATH}/searx/searx/settings.yml
+                sed -i '0,/RE/s/base_url.*/base_url : \"http://${SEARCH_ENGINE_ONION_HOSTNAME}\/' ${SEARCH_ENGINE_PATH}/searx/searx/settings.yml
             fi
         fi
     fi
     fi
     sed -i "s|secret_key.*|secret_key : \"${SEARCH_ENGINE_SECRET_KEY}\"|g" ${SEARCH_ENGINE_PATH}/searx/searx/settings.yml
     sed -i "s|secret_key.*|secret_key : \"${SEARCH_ENGINE_SECRET_KEY}\"|g" ${SEARCH_ENGINE_PATH}/searx/searx/settings_robot.yml
-    sed -i "s|base_url.*|base_url : \"http://${SEARCH_ENGINE_ONION_HOSTNAME}\"|g" ${SEARCH_ENGINE_PATH}/searx/searx/settings.yml
-    sed -i "s|base_url.*|base_url : \"http://${SEARCH_ENGINE_ONION_HOSTNAME}\"|g" ${SEARCH_ENGINE_PATH}/searx/searx/settings_robot.yml
+    sed -i '0,/RE/s/base_url.*/base_url : \"http://${SEARCH_ENGINE_ONION_HOSTNAME}\/' ${SEARCH_ENGINE_PATH}/searx/searx/settings.yml
+    sed -i '0,/RE/s/base_url.*/base_url : \"http://${SEARCH_ENGINE_ONION_HOSTNAME}\/' ${SEARCH_ENGINE_PATH}/searx/searx/settings_robot.yml
 
     # note: this might change to a --tor option in a later version
     if ! grep 'socks5://127.0.0.1:9050' ${SEARCH_ENGINE_PATH}/searx/searx/settings.yml; then