Only time I’ve seen viruses on a Linux/UNIX system, was on my FreeNAS box, in a Samba share, put there by a Windows computer… it was easy to get rid of, it created *.exe files with the same name as the parent folder, with a folder icon (and repeated everytime you double clicked on the exe file, thinking it was a folder), but they all had the same checksum - so I just wrote a cronjob to look for them and delete them…
I did once setup and install a virus scanner on UNIX (Solaris) - ths Sun box was a sendmail relay/MTA (for a hideous Groupwise setup - I kinda hate Microsoft, but Exchange even back then was way ahead of Groupwise), so I used Computer Associates virus scanner binary for sparc there to intercept ALL mail and attachments and scan them, it was free to use…
I don’t run any virus scanner on my Linux desktops… don’t see the need… I may regret that one day… I may rethink this is if Linux desktop market share grows significantly in the next ~5 years…
I remember working with a Mac guru in 1996, and he told me that for the first time ever, there’d been no new Mac viruses for 6 months! This was when Apple was in serious trouble, losing market share exponentially, and as the Apple (Power and motorola 68K) target for virus writers shrunk, they stopped writing new ones… then a bit later on that year, Apple re-hired Jobs, merged with NexT (which Tim Berners-Lee used to create the WWW) and Microsoft injected $150 million cash - thus Apple survived…
Now of course, with 10% or so market share on the desktop, there are lots of trojoans and malware for Mac, but viruses? I’m sure it became “easier” when Apple switched to Intel CPU’s…