I tried stopping bitcoind using bitcoin-cli stop and got the following error.
bitcoin-cli stop error: Could not locate RPC credentials. No authentication cookie could be found, and RPC password is not set. See -rpcpassword and -stdinrpcpass. Configuration file: (/home/user/.bitcoin/bitcoin.conf)
I confirmed that bitcoind is running (using ps -A).
ps -A | grep bitcoind 643 pts/0 00:17:23 bitcoind
bitcoind was started in a datadir on the usb storage. I can kill the process but i want to shut it down in a correct way.