-rpccookiefile=<loc>
       Location of the auth cookie (default: data dir)

  -rpcuser=<user>
       Username for JSON-RPC connections

  -rpcpassword=<pw>
       Password for JSON-RPC connections

  -rpcauth=<userpw>
       Username and hashed password for JSON-RPC connections. The field
       <userpw> comes in the format: <USERNAME>:<SALT>$<HASH>. A
       canonical python script is included in share/rpcuser. The client
       then connects normally using the
       rpcuser=<USERNAME>/rpcpassword=<PASSWORD> pair of arguments. This
       option can be specified multiple times

  -rpcport=<port>
       Listen for JSON-RPC connections on <port> (default: 8337 or testnet:
       14337)

  -rpcallowip=<ip>
       Allow JSON-RPC connections from specified source. Valid for <ip> are a
       single IP (e.g. 1.2.3.4), a network/netmask (e.g.
       1.2.3.4/255.255.255.0) or a network/CIDR (e.g. 1.2.3.4/24). This
       option can be specified multiple times

  -rpcserialversion
       Sets the serialization of raw transaction or block hex returned in
       non-verbose mode, non-segwit(0) or segwit(1) (default: 1)

  -rpcthreads=<n>
       Set the number of threads to service RPC calls (default: 4)

chris@chris-ubuntu:~$ iopd -server -listen -rpcuser=chris -rpcpassword=1234
: Error opening block database.
Please restart with -reindex or -reindex-chainstate to recover.
chris@chris-ubuntu:~$ iopd -server -listen -rpcuser=chris -rpcpassword=1234
: Error opening block database.
Please restart with -reindex or -reindex-chainstate to recover.
chris@chris-ubuntu:~$ iopd -server -listen -rpcuser=chris -rpcpassword=1234
: Error opening block database.
Please restart with -reindex or -reindex-chainstate to recover.
chris@chris-ubuntu:~$ sudo iopd -server -listen -rpcuser=chris -rpcpassword=1234
[sudo] password for chris:

chris@chris-ubuntu:~$
chris@chris-ubuntu:~$ iopd -server -listen -rpcuser=chris -rpcpassword=1234
: Error opening block database.
Please restart with -reindex or -reindex-chainstate to recover.