Are there any banks with a command-line style user interface?
Some banks would allow you to export your transactions as CSV (they call it Excel export, but in many cases it's actually just CSV). However, I would not expect any bank to bother with creating anything like command-line access - return on such investment would be too low.  There are other ways to get information out of the banks, I'm sure - providers like Yodelee must be using something to fetch financial data - but those usually not for general public access.  Also, you can use something like mint.com to aggregate you banking data if you bank doesn't do good export and then export it from there. They have CSV export too.  If you need to do any actions though, I don't think there's anything like you are looking for.