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From a user's point of view, they seem equivalent. Some programs can be installed via apt-get install after adding a link to the sources.list.

Others have to be installed by adding a ppa though command line, and as far as I can see, this method doesn't create an entry in the sources.list.

So there must be a technical difference? And, if at all, what is the difference between a PPA and a repository?

2 Answers 2

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Adding via PPA does add a list. file in /etc/apt/sources.list.d, which is sourced by apt so there is a repository there.

The convenience that add-apt-repository provides is that it not only adds the source, it adds the GPG key of the repository so you don't have to do that manually.

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  • So the only real difference is that adding via PPA adds an entry in form of a file in /etc/apt/sources.list.d, while adding a repository manually usually works by manipulating the /etc/sources.list as a file? That means that repository-links are saved in those two, different locations? Sep 30, 2012 at 0:34
  • Yep, that's it! Sep 30, 2012 at 12:10
  • Wish I'd discovered this sooner, I just upgraded from 12.04 to 14.04 using a clean install. I saved /etc/apt/sources.list but not /etc/apt/sources.list.d/ :-( Now have to re-find and add the repositories for all the software that gives me errors when I try to install it :-( Nov 15, 2014 at 8:43
  • 1
    I am wondering why aren't both PPA and links get saved into sources.list.d? isn't it more organize and unified? why only PPAs get saved to that folder? Jul 23, 2017 at 18:10
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Adding a PPA through command line does create an entry.

Command line:

sudo add-apt-repository ppa:webupd8team/jupiter
sudo apt-get update
sudo apt-get install jupiter

After adding the repository it shows up in Ubuntu Software Center:

enter image description here

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  • I am testing 12.10 but this is the same for any older version that I know of (well maybe not Breezy ;) )
    – Rinzwind
    Sep 29, 2012 at 22:44
  • Thank you for your effort! I was using the terminal and didn't discover any entry in the /etc/sources.list - file. It seems this is because the entries are made in separate files under /etc/sources.list.d/ Sep 30, 2012 at 0:39

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