PPAs or Personal Package Archives are basically software repositories that are used by Ubuntu systems…
How to scan for viruses with ClamAV on Ubuntu
There aren’t many viruses made for Linux distributions and as such, most people who use such systems don’t ever bother using an antivirus software. Those however who do want to be able to scan their system or other windows-based systems that are connected on a Linux PC through a network, they can use ClamAV. ClamAV is an open source anti-virus engine that is built to detect viruses, trojans, malware and other threats. It supports multiple file formats (documents, executables or archives), utilizes multi-thread scanner features and receives updates for its signature database at least 3-4 times a day.