sudo service bitcoind start
then wait...
then
bitcoind getinfo
You should get something like this (old example):
{
"version" : 80600,
"protocolversion" : 70001,
"walletversion" : 60000,
"balance" : 0.00000000,
"blocks" : 225436,
"timeoffset" : 0,
"connections" : 9,
"proxy" : "",
"difficulty" : 4367876.00084220,
"testnet" : false,
"keypoololdest" : 1389424771,
"keypoolsize" : 103,
"paytxfee" : 0.00000000,
"errors" : ""
}
Connections should be>0.
Blocks should go up with repeated runs until bitcoind is synced up. Then it would go up every ~10mins only.