If your source list is broken and need to be fixed or you want to add some new PPA's, there's an online tool available which can create your own source.list. This source list generator tool can be found here.
How does it work?
It works very easy, just select your country and which version of Ubuntu you're using and then select the repositories you want. Keep in mind that the repositories mentioned under Ubuntu Branches, Ubuntu Updates and Ubuntu Partner Repos need to be selected since these are very much needed in order to keep your system up-to-date. The 3th parties Repos can be selected if these are needed or required.
When the required PPA's (repositories) are selected, press the button Generate List at the bottom of the site. A source.list will be generated and also the commands to add the authentication key's will be generated. This can be copied and pasted in the original source.list file, best is to overwrite the existing data with the new data to avoid double entry's.
How to modify the existing source.list?
Open a terminal and type the following command:
- sudo gedit /etc/apt/sources.list.
- enter your password when asked for it.
- copy the generated source.list data from the website
- in Gedit, select all text and press the Delete button.
- then paste the new data in the source.list file and save the file by pressing Ctrl+S.
- close gedit
Now the new source.list has to be reloaded. This can be done by typing the following command in a terminal;
- sudo apt-get update.
It is possible that some (new) repositories can't be loaded. The reason for this is that the authentication key is not imported. The command sudo apt-get update shows which repositories couldn't be loaded. On the same website, which generated the source list, the commands for importing the authentication key is also generated, check the site which command is needed to import the missing authentication key.
Commands for importing keys starts with:
- sudo apt-key adv
- wget -q
Copy the command and paste the command in a terminal by pressing Ctrl+Shift+V. The authentication key wil then be imported. If this is done, execute the command sudo apt-get update to reload the source.list to ensure that all lines will be reloaded.