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awk logic for tailing and printing

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# 8  
Old 11-24-2013
Quote:
Originally Posted by Scrutinizer
Try:
Code:
awk '{n=$0; p=p n ORS} NR>m{ sub(/[^\n]*\n/,x,p)} END{if(n~s) printf "%s",p}' m=200 s=FAILED

this worked!!!

anyway I can add a "else" into it to print the entire output in the event the last line of the output doesn't contain the "FAILED" string?

so the logic i'm after is,

if the last line of the output contains a string, print x amount of lines in the output received. this requirement has been satisfied with your awk code.

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
# 9  
Old 11-24-2013
Try this might help

Code:
$ process Blah Blah | awk '{print >"tmp"}END{print /Failed/ ? NR : 99 }' | \
while read line; do [ "$line" -ne 99 ] && awk -v start=$line 'NR>=(start-200) && NR<start' tmp && rm -rf tmp || cat tmp && rm -rf tmp;done

OR

Code:
$ process Blah Blah | awk '{print >"tmp"}END{print /Failed/ ? NR : 99 }' | \
while read line; do [ "$line" -ne 99 ] && tail -200 tmp && rm -rf tmp || cat tmp && rm -rf tmp;done

Last edited by Akshay Hegde; 11-24-2013 at 12:52 PM..
This User Gave Thanks to Akshay Hegde For This Post:
SkySmart
# 10  
Old 11-24-2013
You could try:
Code:
awk '{n=$0 ORS; p=p n; f=f n} NR>m{ sub(/[^\n]*\n/,x,p)} END{printf "%s", n~s?p:f}' m=200 s=FAILED

But if the output is really lengthy it might run out of memory.

------edit------
A bit more efficient:
Code:
awk '{A[NR]=$0} END{b=A[NR]~s?NR-m+1:1; for(i=(b>0)?b:1; i<=NR; i++) print A[i]}' m=200 s=FAILED

Last edited by Scrutinizer; 11-24-2013 at 01:01 PM..
This User Gave Thanks to Scrutinizer For This Post:
SkySmart
# 11  
Old 11-24-2013
@ Scrutinizer
whether this ?

Code:
$ awk '{print >"tmp"}END{ system(sprintf("%s", /FAILED/? "tail -200 tmp" : "cat tmp" ))  }'

to delete tmp
Code:
$ awk '{print >"tmp"}END{ system(sprintf("%s", /FAILED/? "tail -200 tmp && rm -rf tmp" : "cat tmp && rm -rf tmp" ))  }'

# 12  
Old 11-24-2013
@Akshay, yes something like that should work. I would avoid using rm -rf like that (risky), simply rm. Also you need to know if the temporary file exists and if not use something else, or use a temporary file name that is guaranteed not to exist, and typically use something in the /var/tmp directory..
# 13  
Old 11-24-2013
Quote:
Originally Posted by Scrutinizer
You could try:
Code:
awk '{n=$0 ORS; p=p n; f=f n} NR>m{ sub(/[^\n]*\n/,x,p)} END{printf "%s", n~s?p:f}' m=200 s=FAILED

But if the output is really lengthy it might run out of memory.

------edit------
A bit more efficient:
Code:
awk '{A[NR]=$0} END{b=A[NR]~s?NR-m+1:1; for(i=(b>0)?b:1; i<=NR; i++) print A[i]}' m=200 s=FAILED

this is just perfect!

i'm curious, how did you become so proficient at awk? did you take a specific class? i'm pretty sure they dont go into any significant lenght of training on it at any colleges. so i wanna know how you became so good at it that you can pretty much come up with solutions to any problem (using awk). is awk your favorite programming language? if not, what is? i know this has nothing to do with this thread, i'm just curious.
# 14  
Old 11-24-2013
@Scrutinizer
Yes as you said rm -rf is risky and even its better to use something else instead oftmp. I think from this (post #11 system call) we can overcome from out of memory problem, if file is very lengthy right ?
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