function printPrimary { 
  count=`mongo --quiet --port 3001 mongo/functions.js| wc -l`
  while [ $count -lt 1 ]
  do
    echo "No primary yet: $count"
    sleep 2
    count=`mongo --quiet --port 3001 mongo/functions.js| wc -l`
  done
  port=`mongo --quiet --port 3001 mongo/functions.js | cut -d ':' -f2 `
  echo "port is on $port"
}

  # If restarting, kill the mogo processes and then do 
rm -rf  mongo/d1 mongo/d2 mongo/d3 mongo/logs
  # Setup 3 directories:
mkdir -p mongo/d1 mongo/d2 mongo/d3 mongo/logs
  # If not AWS,	  ignore.  
sudo  -s -- bash -c   '  echo "127.0.0.1 localhost ">> /etc/hosts '
  # Start once mongo instance
mongod --dbpath mongo/d1 --port 3001 --oplogSize 100 --wiredTigerCacheSizeGB 0.25 --replSet r --bind_ip 127.0.0.1 > mongo/logs/1.log 2>&1  & 
sleep 2
  # In  the mongo shell
mongo --port 3001 --eval "rs.initiate( { _id: 'r', version: 1, members: [ {_id :0, host: 'localhost:3001' } ] } )"

  # Start and add two other replica sets
mongod --dbpath mongo/d2 --port 3002 --oplogSize 100 --wiredTigerCacheSizeGB 0.25 --replSet r --bind_ip 127.0.0.1 > mongo/logs/2.log 2>&1  &
mongod --dbpath mongo/d3 --port 3003 --oplogSize 100 --wiredTigerCacheSizeGB 0.25 --replSet r --bind_ip 127.0.0.1 > mongo/logs/3.log 2>&1  &
sleep 2
mongo --port 3001 --eval "rs.add('localhost:3002')"
sleep 2
mongo --port 3001 --eval "rs.add('localhost:3003')"
sleep 2
  # Look at the status
mongo --port 3001 --eval "rs.status()"

echo "Let us sleep a really long time, 30 seconds"
sleep 30

/home/mark/temp# mongo --port 3001 --eval "rs.status()" | grep -i state

  # Lets setup the functions. 
echo "
cfg = rs.conf();
cfg.members[0].priority = 3;
cfg.members[1].priority = 2;
cfg.members[2].priority = 1;
rs.reconfig(cfg);
" >> mongo/reconfig.js

echo '
function pcheck() {
  s = rs.status()
  s.members.forEach( 
    function(myDoc) { 
      if (myDoc.stateStr=="PRIMARY") 
        { print( myDoc.stateStr + " " + myDoc.name ) }
      }
    );
}
pcheck()
' > mongo/functions.js

  # Lets print out the hosts in the replica set
mongo --port 3001 --eval "rs.status()" | grep name
  # Remove a host
mongo --port 3001 --eval "rs.remove('localhost:3003')"
sleep 1
mongo --port 3001 --eval "rs.status()" | grep name

  # Add host back in
mongo --port 3001 --eval "rs.add('localhost:3003')"
sleep 2
  # Add print out who is primary and secondary
mongo --port 3001 --eval "rs.status()" | egrep 'name|stateStr'

  # Redo the prorities, but in practice its no promise for stepdowns.
cat mongo/reconfig.js | mongo --port 3001 
mongo --port 3001 --eval "rs.conf()" | egrep 'host|priority'

mongo --port 3001 --eval "rs.stepDown({secondaryCatchUpPeriodSecs: 10 })"
sleep 5
printPrimary
mongo --port 3001 --eval "rs.status()" | egrep 'name|stateStr'

  # Not let's force it back to the first one --- this is bad in production. 
mongo --quiet  --port 3001 --eval "rs.remove('localhost:3003')"
sleep 5
printPrimary
mongo --quiet --port 3001 --eval "rs.remove('localhost:3002')"
sleep 5
printPrimary
mongo --quiet --port 3001 --eval "rs.status()" | egrep 'name|stateStr'

   # Now add them back in
mongo --quiet --port 3001 --eval "rs.add('localhost:3002')"
sleep 2
mongo --quiet --port 3001 --eval "rs.add('localhost:3003')"
sleep 2
  # Look at the status
mongo --quiet --port 3001 --eval "rs.status()" | egrep 'name|stateStr'


  echo "
  cfg = rs.conf();
  cfg.members[0].priority = 3;
  cfg.members[1].priority = 2;
  cfg.members[2].priority = 1;
  rs.reconfig(cfg);
  " > mongo/reconfig.js
  
cat mongo/reconfig.js | mongo --port 3001 --quiet
cat mongo/reconfig.js | mongo --port 3002 --quiet
cat mongo/reconfig.js | mongo --port 3003 --quiet