How to verify that the system isn't infected with a virus

Question

Does anyone know how to check to see if your system has been infected with any type of malware? I read in an article at zdnet.com that there was a Mac OS X trojan spotted, but the article did not say how to locate whether or not you had been infected. I do not have a virus checker on my computer. Someone gave me a suggestion to go to the terminal and type in the following:
ls /Users/Shared/.*.so
Any comments?

Answer 1

fane_j wrote:
Sally R. wrote:
Someone gave me a suggestion to go to the terminal and type in the following:
ls /Users/Shared/.*.so
This was published on MacWorld's site, and it's not a very good tip. Try this instead
ls -la /Users/Shared/*.so
Turns out I was wrong about that. Somebody else suggested something even more complicated and got this reply:
By bastion
Fri Feb 24 08:49:05 PST 2012
PeterSParker said
Your terminal statement has an extra "." in it that prevents it from working.
Also, you should add the options -alR to show what is happening, and to search subdirectories.
The revised command looks like this:
ls -alR /Users/Shared/*.so
The above is completely wrong. The command as shown in the article is appropriate.
The "." is not extra and doesn't prevent the command from working. It's specifying that you're listing files that start with a period and end with ".so" with anything in between being matched.
Because you're explicitly searching for things that start with "." you don't need the -a flag.
Because you only care about simple existence and not any metadata you don't need -l.
Because the files of interest are installed in /Users/Shared directly, and not subfolders thereof, you don't need -R.