On Ubuntu, the QGIS project provides packages for the LTR, Latest Release (LR), and development versions (DEV). For this book, we recommend installing the LTR version. The LTR version is the current most stable version of the software.

To avoid conflicts that may occur due to incompatible packages, make sure that you only add one of the package source options. The specific lines that you have to add to the source list depend on your OS version. The following version is the latest release for Debian stretch:

deb     https://qgis.org/debian stretch main
deb-src https://qgis.org/debian stretch main

After choosing the repository, we will add the qgis.org repository's public key to our apt keyring. This will avoid the warnings that you might otherwise get when installing from a non-default repository. Run the following command in Terminal:

wget -O - https://qgis.org/downloads/qgis-2017.gpg.key | gpg --import
gpg --fingerprint CAEB3DC3BDF7FB45
gpg --export --armor CAEB3DC3BDF7FB45 | sudo apt-key add -

If necessary, you might need to make adjustments based on your system. For an updated list of supported Ubuntu versions, check out http://www.qgis.org/en/site/forusers/alldownloads.html#debian-ubuntu. By the time this book goes to print, the key information might have changed. Refer to http://www.qgis.org/en/site/forusers/alldownloads.htm for the latest updates.

Finally, to install QGIS, run the following commands. The first will fetch any updates to packages on your system; the second will install QGIS, the Python library, and the GRASS plugin:

sudo apt-get update
sudo apt-get install qgis python-qgis qgis-plugin-grass

This book has been written based on a QGIS installation on a Windows operating system. There may be slight visual changes between operating systems, especially the screenshots.