How do I install a package outside of the APT database?

Question

I am new to Linux, so this might sound like a simple question, but how do I install a package outside of the APT database? I am trying to install the following package:

https://launchpad.net/ubuntu/+source/pdb2pqr

Any help will be appreciated. Thank you!

Answer 1

Let's assume you are currently running Huriste Hippo (21.04).

1. Expand "The Hirsute Hippo (current stable release)" section.

   You will see a list of Package files.

2. Select and download the the *.deb (*.ddeb) files for your architecture.

   For AMD64, you would pick:

   • pdb2pqr-dbgsym_2.1.1+dfsg-7build1_amd64.ddeb - Debug symbols for pdb2pqr. Note, this is probably optional, unless you need to debug the software.
   • pdb2pqr_2.1.1+dfsg-7build1_amd64.deb - Preparation of protein structures for electrostatics calculations
   • pdb2pqr-doc_2.1.1+dfsg-7build1_all.deb - Example files accompanying pdb2pqr

3. Open a terminal and execute the following commands.

   Let's assume you downloaded these files to your Downloads directory.

   cd ~/Downloads
   

4. Add the universe repository so Ubuntu can download other dependent packages you may need. Also this is needed for the gdebi command below.

   sudo apt-add-repository universe
   sudo apt update
   

5. Install gdebi, a tool to allow you to install *.deb files and automatically install their dependencies.

   sudo apt install gdebi-core
   

6. Install your downloaded packages.

   sudo gdebi pdb2pqr_2.1.1+dfsg-7build1_amd64.deb
   sudo gdebi pdb2pqr-doc_2.1.1+dfsg-7build1_all.deb
   sudo gdebi pdb2pqr-dbgsym_2.1.1+dfsg-7build1_amd64.ddeb