What is a good free linux antivirus? [duplicate]

You actually don't need an antivirus. But anyways, there's a free, open-source anti-virus called ClamAV. It detects trojans and malwares. Source code : https://github.com/Cisco-Talos/clamav Install :

sudo apt install clamav

It's a cli-based tool, You can see how to use it from the internet or just running man clamav

also there's a gui one called clamtk

To install it run :

sudo apt install clamtk