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Can I tail the log on a Cisco Router? I have 'logging buffered 51200' and a debug running. I can see the packets with 'show log'. Can I tail this?

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If you need to jump quickly to the last lines of the log, term length 0 before sh log. –  petrus Sep 11 '11 at 12:23

3 Answers 3

up vote 8 down vote accepted

Sure, run logging monitor debug (or any other level) then term mon.
Log will be displayed on your (and only your) telnet/ssh session.
If you are using the console use logging console.

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To clarify a bit, "logging monitor <level>" set globally the level, then "terminal monitor" enable session per session to display log on the terminal (using the globally defined level). –  radius Sep 11 '09 at 6:29
    
This is a tail -f rather than a tail, I'm not sure what the original poster had in mind. –  Aaron Aug 2 '11 at 14:35

Sending to syslog is the better way to do, but here's a trick you might find useful:

You can do "show logging | begin regexp" and it will show you the log starting at any lines matching that regexp.

That way, if you have your logs being time-stamped (you do, right?) You can something like:

show logging | begin ^Sep 3*

(note there is a double space after "Sep" but this text editor eats it) and it will show you all logs starting from September 3rd, for example.

Requires some experimentation to get it right. :)

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The best way to do this is to set a syslog host and by sending data log to it you can watch events in realtime. You could also try adjusting the console messages with logging console debug

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