If you're a Mac switcher and you're looking for a tool like the awesome ProcMon or FileMon tool from SysInternals on the Mac, look no further than the built-in fs_usage tool.

sudo fs_usage

This will start dumping out filesystem activity by any process; man fs_usage to get details on how it works.

It's very cool having this sort of capability built in instead of having to hunt down a third party tool.

It's also cool to look at the file system activity logs on the Mac and see how much more sensible they are than the mess of activity that happens whenever you do anything on Windows.  I think the best part is that there's no RegMon equivalent because on the Mac, there's no registry.

I like the registry concept, I do.  But run RegMon for a few minutes on a Windows box and scan through the registry activity that's happening to see a few thousand reasons why it's just gone wrong.