Is it possible to use tail and grep in combination?

Question

I am trying to tail a user in production log.

Is it possible to use

tail -f grep "username"

It's a little more efficient to use `tailf` instead of `tail -f`. — Pointy, Jan 02 '13 at 15:01

score 14 · Accepted Answer · answered Jan 02 '13 at 15:00

14

Yes - You use pipe. i.e.

tail -f <some filename> | grep 'username'

answered Jan 02 '13 at 15:00

Ed Heal

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nakib · Answer 2 · 2014-02-25T15:03:03.473

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Yes, you can just use a pipe

tail -f fileName | grep username

edited Feb 25 '14 at 15:03

answered Jan 02 '13 at 15:04

nakib

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Either use `tailf` or `tail -f`. – alk Jan 02 '13 at 17:10

score 3 · Answer 3 · answered Jan 19 '14 at 06:08

The ack command, which is a grep-like text finder, has a --passthru flag that is designed specifically for this.

Since ack automatically color codes matches for you, you can use it to search the output of a tailed log file, and highlight the matches, but also see the lines that don't match.

tail -f error.log | ack --passthru whatever

All the lines of the tailed log will show up, but the matches will be highlighted.

ack is at http://beyondgrep.com/

score 1 · Answer 4 · answered Jan 19 '14 at 05:46

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factually I have found it to be more efficient to use: grep username filename | tail

answered Jan 19 '14 at 05:46

user3211496

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Is it possible to use tail and grep in combination?

4 Answers4