Check status of daemon? I have started bitcoind on my linux box. How can I ask it what its status is? I assume it is downloading the blockchain and will continue to do so for hours or days. How can I find out where it is in this process?
I found the easiest way to do this (version 0.12) is to issue the command (not case sensitive):

bitcoin-cli getblockchaininfo


Then, compare the blocks received field, to the headers field. The blocks received should increase steadily until it matches the headers field, at which point the client is synced.

Once the client is synced you can check if the client is accepting inbound transactions by issuing the command:

bitcoin-cli getconnectioncount 


If you have 0 connections, something is wrong. If you have 8 connections, then it means you are only doing outbound connections (which might be the case if you just want to use your client to execute your own personal transactions, not verify everyone else's). If you have more than 8 connections, then it means you are accepting inbound connections and are acting as a full node (good for you).

Two additional ways to get information about your node is to use GetNetTotals which returns information about network traffic, including bytes in, bytes out, and the current time, and GetNetworkInfo which provides information about your connections to other nodes.