@tumic:
I'm using avast as a daily scanner for malware on a shared web hosting server, based on RedHat, so is not possible to use avast-fss.
Anyway is not a bug, so thanks for hint about /etc/default/avast options.
Another question, can we get some detailed reports from scan process (like number of files scanned, number of infected files, etc)?
And it is possible to add a remove/quarantine option to scan process?