/usr/bin/bitcoind --help
Bitcoin version v0.8.5.0-gef14a26-beta

Usage:
  bitcoind [options]
  bitcoind [options] <command> [params]  Send command to -server or bitcoind
  bitcoind [options] help                List commands
  bitcoind [options] help <command>      Get help for a command

Options:
  -?                     This help message
  -conf=<file>           Specify configuration file (default: bitcoin.conf)
  -pid=<file>            Specify pid file (default: bitcoind.pid)
  -gen                   Generate coins (default: 0)
  -datadir=<dir>         Specify data directory
  -dbcache=<n>           Set database cache size in megabytes (default: 25)
  -timeout=<n>           Specify connection timeout in milliseconds (default: 5000)
  -proxy=<ip:port>       Connect through socks proxy
  -socks=<n>             Select the version of socks proxy to use (4-5, default: 5)
  -tor=<ip:port>         Use proxy to reach tor hidden services (default: same as -proxy)
  -dns                   Allow DNS lookups for -addnode, -seednode and -connect
  -port=<port>           Listen for connections on <port> (default: 8333 or testnet: 18333)
  -maxconnections=<n>    Maintain at most <n> connections to peers (default: 125)
  -addnode=<ip>          Add a node to connect to and attempt to keep the connection open
  -connect=<ip>          Connect only to the specified node(s)
  -seednode=<ip>         Connect to a node to retrieve peer addresses, and disconnect
  -externalip=<ip>       Specify your own public address
  -onlynet=<net>         Only connect to nodes in network <net> (IPv4, IPv6 or Tor)
  -discover              Discover own IP address (default: 1 when listening and no -externalip)
  -checkpoints           Only accept block chain matching built-in checkpoints (default: 1)
  -listen                Accept connections from outside (default: 1 if no -proxy or -connect)
  -bind=<addr>           Bind to given address and always listen on it. Use [host]:port notation for IPv6
  -dnsseed               Find peers using DNS lookup (default: 1 unless -connect)
  -banscore=<n>          Threshold for disconnecting misbehaving peers (default: 100)
  -bantime=<n>           Number of seconds to keep misbehaving peers from reconnecting (default: 86400)
  -maxreceivebuffer=<n>  Maximum per-connection receive buffer, <n>*1000 bytes (default: 5000)
  -maxsendbuffer=<n>     Maximum per-connection send buffer, <n>*1000 bytes (default: 1000)
  -paytxfee=<amt>        Fee per KB to add to transactions you send
  -daemon                Run in the background as a daemon and accept commands
  -testnet               Use the test network
  -debug                 Output extra debugging information. Implies all other -debug* options
  -debugnet              Output extra network debugging information
  -logtimestamps         Prepend debug output with timestamp
  -shrinkdebugfile       Shrink debug.log file on client startup (default: 1 when no -debug)
  -printtoconsole        Send trace/debug info to console instead of debug.log file
  -rpcuser=<user>        Username for JSON-RPC connections
  -rpcpassword=<pw>      Password for JSON-RPC connections
  -rpcport=<port>        Listen for JSON-RPC connections on <port> (default: 8332 or testnet: 18332)
  -rpcallowip=<ip>       Allow JSON-RPC connections from specified IP address
  -rpcconnect=<ip>       Send commands to node running on <ip> (default: 127.0.0.1)
  -rpcthreads=<n>        Set the number of threads to service RPC calls (default: 4)
  -blocknotify=<cmd>     Execute command when the best block changes (%s in cmd is replaced by block hash)
  -walletnotify=<cmd>    Execute command when a wallet transaction changes (%s in cmd is replaced by TxID)
  -alertnotify=<cmd>     Execute command when a relevant alert is received (%s in cmd is replaced by message)
  -upgradewallet         Upgrade wallet to latest format
  -keypool=<n>           Set key pool size to <n> (default: 100)
  -rescan                Rescan the block chain for missing wallet transactions
  -salvagewallet         Attempt to recover private keys from a corrupt wallet.dat
  -checkblocks=<n>       How many blocks to check at startup (default: 288, 0 = all)
  -checklevel=<n>        How thorough the block verification is (0-4, default: 3)
  -txindex               Maintain a full transaction index (default: 0)
  -loadblock=<file>      Imports blocks from external blk000??.dat file
  -reindex               Rebuild block chain index from current blk000??.dat files
  -par=<n>               Set the number of script verification threads (up to 16, 0 = auto, <0 = leave that many cores free, default: 0)

Block creation options:
  -blockminsize=<n>      Set minimum block size in bytes (default: 0)
  -blockmaxsize=<n>      Set maximum block size in bytes (default: 250000)
  -blockprioritysize=<n> Set maximum size of high-priority/low-fee transactions in bytes (default: 27000)

SSL options: (see the Bitcoin Wiki for SSL setup instructions)
  -rpcssl                                  Use OpenSSL (https) for JSON-RPC connections
  -rpcsslcertificatechainfile=<file.cert>  Server certificate file (default: server.cert)
  -rpcsslprivatekeyfile=<file.pem>         Server private key (default: server.pem)
  -rpcsslciphers=<ciphers>                 Acceptable ciphers (default: TLSv1+HIGH:!SSLv2:!aNULL:!eNULL:!AH:!3DES:@STRENGTH)