Adding Repositories in Ubuntu
Programs that you can install using apt-get on your Ubuntu Linux system are stored in repositories. Ubuntu software repositories are organized into four separate areas based on the level of support offered by Ubuntu or third parties. The repository structure of organization is as follows:
- Main - preconfigured and your main Ubuntu support software
- Restricted - software with restricted licensing
- Universe - third-party free and open source software
- Multiverse - commercial software, closed source, free or pay
Universe repositories are by and large are numerous made up of individually or developer maintained sources of private development projects. Software developers often maintain their own repositories, from which software packages can be downloaded and installed directly. These are privately controlled repositories that are not monitored by a control so you should be careful what repositories that you trust and add to your list. Some repositories could contain malicious software. Basically, anyone can create a repository, and software to it, and publicly offer that software for users, for better or for worse.
PPA repositories or Personal Package Archives are a special type of Universe repository used to store experimental source packages still under development. Such software has not been approved by the Debian or Ubuntu developers (but may eventually become an accepted package). Use this software at your own risk just like any other third party repository software.
The Ubuntu installer references both Main and Restricted when adding components during installation. These repositories, or sometimes called repos for short, are already defined in your repositories sources list: /etc/apt/sources.list View them:
cat /etc/apt/sources.list|less
This repositories list can be edited by directly opening the text file sources.list or can be managed via a graphical user interface.
