I understand that viruses cannot install themselves under Linux because under
Linux a root password is needed for installing programs (I have come accross
some exceptions, though, like a version of KBasic). And I came accross other
exceptions, as well.
I also understand that another thing is that, unlike under Windows, a virus
cannot enter your PC from the Internet or from the local network automatically,
you would have to download it and then run the virus that you desire so much.
And then the surprise might be that it is not compatible with your OS.
Am I right ?
I am sure that when Linux becomes more widespread, lots of trojans will be
written for Linux, also, but these will exploit the vulnerability of the user
itself, not the vulnerability of the system. There will be clever ways of
convincing careless users to run certain programs.
As for being infected automatically and in large numbers, with malware
produced and copied in industrial amounts like today, this will be simply
impossible, like cheerfully swimming in molten iron.