There are several methods to detect the presence of infected files. The most obvious solutions are plug-ins to browsers and email clients. Thunderbird has a plug-in called clamdrib that scans attachments for virii. Firefox, however, only has an older plug-in to integrate with clamav for virii.
Client (HTTP, email) program based virus scanning has its limitations. A more complete method to scan for virii is clamfs. clamfs (clam file system) is a file system that relies on ClamAV to scan for virii. The coolest part is that it scans virii on-demand. In other words, you may have 200GB of files in a clamfs mount point, but it only scans a file when you access it. Furthermore, clamfs maintains a cache to keep track files that are already scanned to speed up the access to frequently used files.
clamfs is a virus scanning solution that is unique to Linux (and other Unix-like operating systems) because of the availability of FUSE (file system in user space). FUSE makes it easy to create the pretense of a file system without requiring a lot of administrator duties. Indeed, clamfs can be set up by an end-user once the package is installed. This means that individual end users can choose which subfolders to go through clamfs for automated virus scanning.
Last, but not least, one can always use clamav to actively scan files and folders. Install the clamav package and use the command clamscan to scan files and folders. This method is the most “traditional” method of virus scanning.