"geth attach" - Geth Client Console

Ethereum Tutorials - Herong's Tutorial Examples

∟"geth attach" - Geth Client Console

This section describes 'geth attach' command to attach as a client JavaScript console to a running Ethereum node.

To avoid data corruptions, on a single Ethereum database, we are not allowed to run two instances of Ethereum node server.

If you have one "geth" command running on the Ethereum database of C:\Users\herong\AppData\Roaming\Ethereum\geth as an Ethereum node server, and you try to start another Ethereum node server on the same database, you will get the following error:

C:\> \herong\bin\geth --light

Maximum peer count                       ETH=0 LES=100 total=25
Fatal: Error starting protocol stack: datadir already used by another process

But you can run Geth in client mode to attach to the running Ethereum node server and provide a JavaScript console:

C:\> \herong\bin\geth attach
Welcome to the Geth JavaScript console!

instance: Geth/v1.8.1-stable-1e67410e/windows-386/go1.9.2
 modules: admin:1.0 debug:1.0 eth:1.0 net:1.0 personal:1.0 rpc:1.0 
 txpool:1.0 web3:1.0

> eth.syncing
false
> eth.blockNumber
5160607
>