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I often use tail -f | grep someregex on log files. I have grep liased to grep ---color=auto so my matches are highlighted. If I want to see my matches in the context of the whole stream, how would I go about that? Essentially, I want to use tail + grep as a highlighter.
Pete
Posted 2013-11-13T19:46:34.310
Reputation: 277
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To see your matches in context, use the -C option. To see all the lines, use a huge argument to -C, e.g.,
tail -f yourlogfile | grep -C9999 someregex
garyjohn
Posted 2013-11-13T19:46:34.310
Reputation: 29 085
Not sure why I didn't try this, I just assumed the context arguments wouldn't work on streams. Thanks. – Pete – 2013-11-13T20:05:47.667
0
If I understand well, it is what you are looking for:
grep "someregex" yourFile
It will print the lines where the "regex" matches.
Manolo
Posted 2013-11-13T19:46:34.310
Reputation: 335
I'm using this on a log file, I would like to see it output in real time w/o interaction, hence the tail -f, but want to highlight matches – Pete – 2013-11-13T19:57:15.403
The matches are highlighted with your command. So what is your desired output? – Manolo – 2013-11-13T20:01:24.800
Well, I think I understand you now, since I've seen @garyjohn answer. Is it your desired behavior? – Manolo – 2013-11-13T20:04:26.577
1Could you please clarify? What do you mean by the whole stream? If you want the whole stream, just don't use
tail, rungrep somepatterndirectly. Could you give an example of the kind of process you are monitoring? – terdon – 2013-11-13T19:49:15.847if I am tailing a log file, grepping on error messages, but want to see it in context of some debug messages leading up to that match, in real time. – Pete – 2013-11-13T19:54:00.157