Fatal: Unable to attach to remote geth: no known transport for URL scheme "c"
翻译后的意思是这样 致命：无法附加到远程geth：没有已知的URL方案传输“c”
我们只需要把原先geth attach 改为 geth attach ipc:\\.\pipe\geth.ipc 即可
C:\Users\Administrator>geth attach ipc:\\.\pipe\geth.ipc
Welcome to the Geth JavaScript console!
instance: Geth/v1.8.11-stable-dea1ce05/windows-amd64/go1.10.2
coinbase: 0xb6ebec2158290e4a5a461005342a2ca5696fcf69
at block: 0 (Thu, 01 Jan 1970 08:00:00 CST)
datadir: C:\Users\Administrator\AppData\Roaming\Ethereum\testnet
modules: admin:1.0 debug:1.0 eth:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txp
ool:1.0 web3:1.0
>