There are a few linux scripts out there that will do it using the core reference client.
BUT, the biggest issue is figuring out the fees.
Think about it, if you get some
BTC in now and just want to forward it out the core wallet is going to use 0.00082833 BTC/kB
If it's a small transaction you're going to eat up a lot of it.
bitcoind sendtoaddress WHERE_YOU_WANT_IT_TO_GO amount of coin
Will send all, you would have to do some math 1st to leave some for fees
Should get you your balance (it's been a while no idea it should work). And you can do some math from there.
-Dave