This section explains how to install software and open repository sites (basically, library sites of software compatible with this Linux distribution) packaged with but not enabled in Ubuntu by default. You also learn how to add third-party repositories.
The more repositories, the more software you have access to. Open the Software Sources repository GUI application via System menu > Administration > Software Sources.
I handle this by simply checking everything in the Ubuntu and third-party software sources tabs: Updates, Important, and Recommended. In the pulldown, I switched “Long-Term Support” to Normal.
Adding New Third-Party Repositories
Advanced users may want to add non-supported (by anyone but the authors) software collections or single programs with their own repositories.
Open the Applications menu and select Add/Remove, and enter apt key manager in the Search window. Set it to access “All Available Applications” if the search turns up nothing. Click the Apt Key Manager entry in the list which appears. This program takes a user-entered public key ID corresponding to a repository, finds the key on the PGP keyserver network, and adds it to the keyring Apt uses to determine whether software has a digital signature from a legitimate source.
Open the System menu and click Administration > Software Sources, then click Add and enter the deb repository entry in the text box. Here's an example that will get you access to a repository with applications and codecs that aren't available in the repositories that come by default with the Ubuntu package. The following is a deb repository entry:
deb http://packages.medibuntu.org/ hardy free non-free
You'll see the message
The information about available software is out-of-date
and it will reload the package list. After that, you'll see the following window shown in Figure 2.
Figure 2 ”No public key” error message
You'll get a public key missing/can't authenticate error. Copy the character sequence after NOPUBKEY to the clipboard (that is the Key ID for the software repository). Then do the following:
- Open Applications > System Tools > Apt Key Manager.
- Paste the clipboard into the Key ID text box.
- Click Add. You'll get no authentication errors when you add software from the new repository.
To install software packages, you can use the Add/Remove option in the Applications Menu (a simplified package manager interface), or open System > Administration > Synaptics Package Manager. Here you can either browse through the package lists by section or if you know the name, click the Search icon and enter it into the text box.