I need to analyze the files uploaded to my site. What options do I have? I'm in a dedicated, so I can install things on Linux.
Is it normal for a site to analyze every file uploaded? Can this be done fast (eg: right after the file is uploaded), or is it something that a Cron job should do?
Are there any PHP libraries to do this?
The files I'm most worried about are images, because they are shown in every user's browser.
Note: I never worked with an antivirus, be kind =)