You can communicate with your nodes over RPC (outside of the Geth Terminal) to execute methods defined in web3 API. For instance, we can use CURL or some other command-line HTTP-fetching utility to request Geth's version over RPC as follows:

curl -X POST --data '{"jsonrpc":"2.0","method":"web3_clientVersion","params":[],"id":67}' -H 'content-type: text/plain;' http://127.0.0.1:8545/
 {"jsonrpc":"2.0","id":67,"result":"Geth/v1.7.2-stable-1db4ecdc/linux-amd64/go1.9"}}