Estimates vary, but generally it is believed that there are 100 to 500 Linux viruses out there. The tiny number of Linux viruses that do exist have never resulted in a significant outbreak. In comparison to the plethora of viruses and worms in Windows-based platforms, the volume of Linux viruses is insignificant. So this leads us to two questions: why are there so few Linux viruses and are Linux anti-virus tools necessary?

If Linux is hardly affected by viruses, why do system administrators use anti-virus software on their Linux email servers? Because an anti-virus scanner on a mail server can serve as another level of defense for Microsoft Windows desktop users.

There has been a lot of debate recently over whether or not it's a good idea to run an anti-virus program if you're using Linux. I hope to clear up a common misunderstanding: An anti-virus program running on Linux is designed to detect Windows viruses, so that they aren't spread, unknowingly, by the Linux user. This article explains when you should run a Linux anti-virus, and what exactly they do.

Often, even if we do catch a virus, it's not so difficult to eradicate it using installed anti-virus—but if your system has been crippled, try using Linux to scan the drive for viruses instead. As any Linux veteran knows, one of Linux's greatest uses is fixing unbootable drives—recovering files, deleting files, and even killing viruses.

Viruses. They happen to almost everyone. If they don’t happen to you, it’ll be your cousin Stan who get joins the malware-of-the-month club, and you’re the only person he knows who can fix a computer. The problem is, things are so screwed up that Windows won’t even start properly.

Historically, there have been some [gnu/linux effecting viruses]. And there are browser exploits, of course, that no operating system is completely immune from. However, viruses, as we think of them in the Windows world, are highly unusual.

After having travelled through the virus infested land of Windows, new Linux converts often have queries about viruses on their Linux systems. Here I will demystify all those queries related to Viruses, Antivirus software’s etc once & for all.

This is the screenshot of the cnet's download.com which shows the most popular downloads for windows. The first five positions are taken by anti-virus software :-).

Anti-virus companies play a losing game. Casting their nets wide, they catch common, malicious viruses and worms (known to the industry as “malware”), but it may take days before their software updates can prepare your computer for the next attack. By then it could be too late.