USC vs. synaptic vs. apt-get vs. tarball

[afulldeck]

To clarify this further:

There are two ways to install, update and uninstall programs.

1. DIY (do it yourself)
2. Through the package manager

There are two main package managers for Linux. Ubuntu uses one called Debian, or .deb for short. (The other is RPM.) The package manager has several advantages, including automatic downloading, installing, and detection of updates.

To install a program, you tell the package manager to install a .deb file. The .deb file decides how to install, and whether or not to put an entry into the menu.

.deb files can be manually downloaded, or you can simply tell the package manager to have a look at some PPAs. A PPA is a storage space for .deb files, and by using them, the package manager can automatically find applications and detect when they need to be updated. The package manager also checks for dependencies and maintains consistency, preventing you from installing or uninstalling applications that would break their dependencies.

Canonical (Ubuntu's sponsor) provides several PPAs by default, but you can add more if you trust them. For example, if you want the latest GIMP, you can add GIMP's PPA — but of course Canonical cannot promise that it would work with your version of Ubuntu. You take the risk when you add a PPA (although if it breaks something, you can remove the PPA and undo what you did, using the package manager of course).

The package manager can be accessed in different ways. They include — but are not limited to — dpkg, aptitude, apt-get, Synaptic Package Manager, and the Ubuntu Software Centre. Use whichever you prefer.

Generally, you do not want to go the DIY route, as you lose all the advantages of the package manager.

A few applications do not provide PPAs, but do provide .deb files. In those cases, you still have the advantage of using the package manager, but you have to manually download the .deb file and check for updates, as the package manager needs a PPA to perform those two functions.

I hope that's sufficiently clear.

That was excellent. So if I was using the Ubuntu Software Center how do I add the PPA through the USC? When I pull up the USC there doesn't seem to be any direct connection.

[Paddy Landau]

That was excellent. So if I was using the Ubuntu Software Center how do I add the PPA through the USC? When I pull up the USC there doesn't seem to be any direct connection.

First, an explanation of how to specify a PPA. There are two ways. I shall use yad as an example.

1. Specify the full line, which takes the following format.
   

   deb [PPA_URL] [YourUbuntuVersion] main

   (The last item "main" may change, but you will be told when that is the case.) Using yad, and assuming that you are using Precise, you'd have:
   

   deb http://ppa.launchpad.net/webupd8team/y-ppa-manager/ubuntu precise main

2. If — and only if — the PPA is on Launchpad, you can use the following abbreviated line:
   

   ppa:[PPA_abbreviation]

   Again using yad:
   

   ppa:webupd8team/y-ppa-manager

So, how does this work with the Ubuntu Software Centre?

1. Start USC.
2. Menu > Edit > Software Sources > Other Software > Add
3. Type in either the abbreviated line (if it's on Launchpad) or the full line.
4. > Add Source

Screen-shot of the two new lines

Once you have added the PPA, you probably want to make two changes.

1. You probably don't want the source code (unless you are a programmer wanting to change yad), so click on the line ending "(Source Code)" and press Remove.
2. You probably want to remember why you added this PPA, so click on the new item > Edit > type a meaningful comment in the "Comment" box > OK

Screen-shot after making changes

Finally, press Close to close the Software Sources window.

At this point, you want the package manager to update its listings (until it does so, your changes will be ignored). Unfortunately, the USC does not have a button to do this (this should be reported as an error). But you can do so from either Synaptic Package Manager or via the CLI (command-line interface).

1. From Synaptic Package Manager: Press the Reload button. You must close Synaptic Package Manager before using USC again, because Synaptic locks the package manager.
2. From the CLI: Open a Terminal and enter the following command.
   

   sudo apt-get update

[afulldeck]

Again thank you for your complete answer. I've made a record of this for next time I want to add a PPA using USC. (Last time I did everything manual outside the USC.) That said, has anyone thought of adding a button to USC (add PPA?) so one could simply add a ppa with one touch?

[Paddy Landau]

That said, has anyone thought of adding a button to USC (add PPA?) so one could simply add a ppa with one touch?

You can raise this idea as a Brainstorm. But, I rather suspect that it would be rejected, because adding PPAs is an advanced subject — you'd need to research (exactly as you have done!) to discover about the possibility of untrusted PPAs that can put malware on your system. The USC is intended for the "average" user, who would avoid doing this sort of thing.

But try, anyway; you may find that the idea meets with general approval.

[rybnik]

My initial question has been answered to my satisfaction (thank you!), but I'll hold off on marking the thread [solved] for now, as there seems to have been another discussion emerged.

[Paddy Landau]

I'll hold off on marking the thread [solved] for now, as there seems to have been another discussion emerged.

The "solved" marker is for the original question, not for subsequent discussions that may arise. (Strictly speaking, new discussions should go in new threads, but these forums are not strict in that sense.)

Marking your thread as solved serves two purposes: (1) It lets others with a similar problem find the answer; and (2) It saves time for those volunteers who try to solve unanswered questions and problems.

[rybnik]

^Okay. I understand.