save filled form in pdf file in ubuntu

Solution 1:

The feature you're looking for is "Enable Usage Rights in Adobe Reader..." - It's only available in the Acrobat 8 Professional and newer.

In Acrobat 8 Professional the feature can be found here:

Advanced > Enable Usage Rights in Adobe Reader...

This will give users of Acrobat Reader the ability to save interactive forms with their data

Solution 2:

As of 2020, using evince (v3.36, on Ubuntu 20.04 it's just called "Document Viewer"), I can save a PDF form (just using CTRL+S, e.g., saving as a different file name), and then open the new PDF again, and continue editing the form.

(Adobe no longer supports Acrobat Reader for Linux. The latest native Linux version is 9.5.5 dated from 26/04/2013.)