Eu estava pensando em criar um sistema operacional com base ubuntu para vender com modificações e queria saber se preciso de uma permissão ou fazer contrato com a empresa para dar uma taxa para poder vender.
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I was thinking of creating an ubuntu based operating system to sell with modifications and wanted to know if I needed a permit or make a contract with the company to give a fee to be able to sell.
Yes, but... you must abide to the licenses in the initial Ubuntu source code. Many of these licenses require that you distribute the source code of your modifications to the code. This means that folks (or even competitors) can just take your source code and use it (or even sell it).
In practice, you cannot make much money selling software that derives from Open Source code. What you can do, if your OS has some merit, is sell support. This is for instance the "business model" or RedHat's RHEL, and they make money from it (despite the existence of CentOS, which is mostly RHEL-made-free-again).
