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awk logic for tailing and printing

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# 15  
Old 11-24-2013
Try this; not sure if this will be efficient on large files...
Code:
tac file | awk 'NR==1 && !/FAILED/ {exit} NR>200 {exit} 1' | tac

This User Gave Thanks to RudiC For This Post:
SkySmart
# 16  
Old 11-24-2013
@ RudiC brilliant ! nice solution

But if string FAILED is not found then it does not print anything

for example :

This prints 200 lines
Code:
$ awk 'BEGIN{for(i=1;i<=300;i++)print i;print "FAILED"}' | tac | awk 'NR==1 && !/FAILED/ {exit} NR>200 {exit} 1' | tac

whereas this does not
Code:
$ awk 'BEGIN{for(i=1;i<=300;i++)print i;print "FAILED"}' | tac | awk 'NR==1 && !/FFAILED/ {exit} NR>200 {exit} 1' | tac

Modified version of RudyC's solution
Code:
tac file | awk 'NR==1  &&  !/FAILED/{s=1} s || NR < 200' | tac

Tested like this
This prints 200 lines
Code:
$  awk 'BEGIN{for(i=1;i<=300;i++)print i;print "FAILED"}' | tac | awk 'NR==1 && !/FAILED/{s=1} s || NR <= 200' | tac

Whereas this prints all
Code:
$ awk 'BEGIN{for(i=1;i<=300;i++)print i;print "FAILED"}' | tac | awk 'NR==1 && !/FFAILED/{s=1} s || NR <= 200' | tac

Last edited by Akshay Hegde; 11-24-2013 at 11:30 PM..
# 17  
Old 11-25-2013
Quote:
Originally Posted by SkySmart
... basically, printing the last 200 lines of the output should be dependent only on IF the last line of the output contains the word "FAILED".
It should not print anything if FAILED is not found.
# 18  
Old 11-25-2013
@RudiC as you know here requirement is keep on changing...Smilie

from #8
Quote:
......
the next logic is, if the last line of the log does not contain the string "FAILED", then print the entire output. no need to print a select number of lines. just print everything
# 19  
Old 11-25-2013
Rats! Overlooked that - sorry, need to rethink...


EDIT: Well, try that:
Code:
tac file1 | awk 'NR==1 {if(/FAILED/) L=200; else L=1E23}  NR<=L' | tac

or even
Code:
tac file1 | awk 'NR==1 {L=(/FAILED/)?200:1E23}  NR<=L' | tac

Last edited by RudiC; 11-25-2013 at 04:35 PM..
# 20  
Old 11-25-2013
Actually your tac approach is really nice on large file compare my system call inside awk ...

I just modified your approach like this
Code:
tac file | awk 'NR==1  &&  !/FAILED/{s=1} s || NR < 200' | tac
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