I am trying to debug one scenario by checking the logs, here is my command
tail -f eclipse.log | grep 'enimation' | grep -i 'tap'
Basically what I am trying to to is that, of all of the line, I am printing lines with enimation in it, then of all of the animation, I want to see the animation with "tap" in it.
Here is the sammple data for which it is returning empty results
*******enimation error*********TapExpand
*******enimation error*********TapShrink
This is returning empty results.
While if I run this command
tail -f eclipse.log | grep -i 'enimation.*tap'
it returns correct results. Can someone please explain to me, what is the difference between the above two command and why there is a discrepancy in the results. They both seem identical to me.
grep is buffering it's output. To tell GNU grep to spit out output line-by-line you need to use --line-buffered option in grep to make it work:
tail -f eclipse.log | grep --line-buffered 'enimation' | grep --line-buffered -i 'tap'
As per man grep:
--line-buffered
Force output to be line buffered. By default, output is line buffered when standard
output is a terminal and block buffered otherwise.
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