Your first question, like mine, should be … why do I need antivirus software on my sooper dooper Ubuntu machine? If the answer is “I don’t” then I’m not going to argue (I happen to be in your camp, probably sitting next to the cook fire). However, if you’re operating your Ubuntu machine in a corporate environment, you might be forced into installing AV.
I’ve been trying to get Sophos running on an Ubuntu 20.10 box and ran into a few issues. To keep you from going bald (a process that’s helped along by undocumented command line switches) then read on!
If you’re using Sophos you should be able to download the Linux installer from the Sophos website (they say “Linux” but they really mean Ubuntu LTS … but don’t let that deter you, we’re just going to plow on and hope everything works).
After you download the “SophosInstall.sh” file, but before you actually run it … install the following programs (no, the installer doesn’t do any kind of pre-check … annoying).
sudo apt install make, gcc
This should allow the installer to compile a module for on-access scanning if you’re using a kernel that Sophos hasn’t pre-compiled a binary for. Then do the normal “enable execute” on the SophosInstaller.sh and run it
chmod +x SophosInstaller.sh
If you forget to install gcc and make you’ll get an error message telling you that a component wasn’t installed when it tries to compile a new kernel module. The SophosInstaller.sh doesn’t let you reinstall or add components, so you’ll need to run the following (undocumented code)
sudo /opt/sophos-av/engine/talpa_select select
This might all fail, because Sophos doesn’t seem to support the latest version of Ubuntu, like it did on my 20.10 installation … maybe try ClamAV?