How to scan your server for viruses and malware

There are many options how to scan your server for viruses or malware. One of them is clamv software.
1. Here is how to install it e.g. on Centos:
yum install clamav clamd
2. Than refresh the virus database with command:
you can schedule this command as cron task to update virus database periodically
3. To scan whole server for viruses execute command:
ionice -c3 nice -n 19 /usr/bin/clamscan -r --bell -i /

ionice and nice we used to minimize impact of scanning on other applications running on server