Hey, I am android developer, this could be done, but depends on whats in bash scripts.
Though sending data to your MySql should be handled by webservice (sending request to certain url), webservice may be setup to work under your LAN only, though this is your server side I doubt it could be done from my position.
You may think "why not connect to MySql from Android app directly?", well that would mean having authentication data saved within Android code, which is quite easy to reverse engineer and thus creating a huge security breach.
Setting which LAN - could be done, either typing IP or choosing from a list of WiFi connections.