Watching a file another app is writing

[Jon Ribbens]

In article <jsgJh.9412$jx3.2696 at newssvr25.news.prodigy.net>, John Nagle wrote:
>> On Unix a quick shortcut would be to simply read the output of 'tail -
>> f <file>' command...
> 
>     "tail -f" just checks the file size once a second.  It's not doing
> anything exciting.

That's not actually always true these days. *BSD, at least, use
'kqueue' to avoid busy-wait on "tail -f".