How can I install bitdefender antivirus?

It is possible to install BitDefender antivirus via the terminal. You need to first add the repository by doing

sudo apt-add-repository "deb http://download.bitdefender.com/repos/deb/ bitdefender non-free"

Next, get and add the repository key

wget https://download.bitdefender.com/repos/deb/bd.key.asc
sudo apt-key add bd.key.asc

Then

sudo apt-get update

Finally install by doing

sudo apt-get install bitdefender-scanner-gui

Once BitDefender is installed you can launch it with the following command:

/opt/BitDefender-scanner/bin/bdgui

Troubleshooting

If BitDefender fails or crashes when trying to update virus signatures, you can try the following steps taken from here. One additional caveat to this answer is that you may need to wait at least 1 hour from your last attempt to update using the GUI. The application warns about not checking for updates again within that time frame.

sudo touch /opt/BitDefender-scanner/var/lib/scan/bdcore.so.linux-x86_64
sudo ln -fs /opt/BitDefender-scanner/var/lib/scan/bdcore.so.linux-x86_64 /opt/BitDefender-scanner/var/lib/scan/bdcore.so
sudo bdscan --update

Now it may show 0 signatures. However, after your first scan, it will display the correct number of signatures.