"Tailing" grep (Was: cat and grep without destroying file)

[Brian Fahrlander]

     While we've got the attention of the most-able on this subject, I'd 
like to reopen a discussion about a very similar tool: a 'grep' that 
happens on tailing a file.  There have been dozens of times that I'm 
looking for a message number in /var/log/mail.log and would love to see 
only the lines mentioning that message.

     A couple of years ago I asked and got a "maybe you could write 
something", but I actually never could.  It's not as easy as it looks.

     Any chance you guys have seen this done?

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  Brian Fahrländer                 Christian, Conservative, and Technomad
  Evansville, IN                              http://Fahrlander.net/brian
  ICQ: 5119262                         AOL/Yahoo/GoogleTalk: WheelDweller
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