What kind of modifications are you making?
In the current product, you can edit aspects of multiple data connections simultaneously by selecting them and clicking edit. Those aspects are:
- server name
- server port
- db user
- db password
Theoretically, some of the above could probably be changed programmatically by connecting directly to the Tableau Repository (postgres). That kind of direct postgres manipulation can lead to problems and is unsupported though.
It's possible that Interworks Power Tools for Tableau might do this: http://powertoolsfortableau.com/
I'm familiar with the web interface for doing this. I want to be able to script it. I have looked in the Postgres internal repository and the userid is stored in here, but the password is hidden somewhere else
Regarding passwords, if you don't have them yourself, you can't extract them from Server. They will be encrypted. For bulk updating data connections programmatically, you might check out the Interworks Workbook SDK. I haven't used it myself, but it seems like it might do what you need it to. For my part, I've hacked the XML of workbooks or datasources before and simply replaced the servername when I needed to. Totally unsupported and hacky to do that, of course.
I downloaded the workbook SDK and had a look, it doesn't appear to have the functionality required.