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I'd like to know the time when line was appended when file is being tail -f'ed.

Is it possible to configure tail to do something like that?

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up vote 1 down vote accepted

It is possible. Try the following:

tail -f /tmp/log.txt | awk '{ print strftime("%Y-%m-%d %H:%M:%S"), $0; }'
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If you're dealing with log files that you are creating, it may be better practice to have the logging program add timestamps to the log instead of the above – earthmeLon Nov 4 '11 at 15:21
Also this will only tell one the time tail outputted the line. To see this try tail --sleep-interval=300 somefile – waltinator Jan 22 '15 at 15:42
Oops tail only pays attention to --sleep-interval when it is not using inotify. So my example above should be tail ---disable-inotify --sleep-interval=3000 -f somefile – waltinator Jan 22 '15 at 15:55

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