I want to create interactive movies using flash technologies. Do I need to buy a program from adobe to be able to create my flash movies or there are some free software that I can use? I would prefer something for Linux (Ubuntu).
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I need to program in "actionscript" and I would like to know what programs can I use to compile my code.
You might have a look at haXe. It supports Windows, OSX, and Linux.
There are lots of open source alternatives to using Flash CS*, or Flash/Flex Builder. If you are looking for a free IDE, you can check out FlashDevelop at http://www.flashdevelop.org/wikidocs/index.php?title=Main_Page.
There are some really useful libraries, frameworks, editors, utilities, etc located at http://osflash.org/open_source_flash_projects that you can look into. It's a good list of many different alternatives.
Cheers.