grep and display few lines before and after - Page 2

summer_cherry · #8 (**permalink**) 07-23-2008

Code:

awk:
nawk -v ran=$1 -v pat=$2 '{
arr[NR]=$0
if (index($0,pat)!=0)
        line=NR
}
END{
for(i=line-ran;i<=line+ran;i++)
        print arr[i]
}' file

perl:
$pat=shift;
$ran=shift;
open FH,"<a";
while(<FH>){
$arr[$.]=$_;
if (index($_,$pat)>=0){
$line=$.;
}
}
close(FH);
for($i=$line-$ran;$i<=$line+$ran;$i++)
{
print $arr[$i];
}

cv_pan · #9 (**permalink**) 09-25-2008

Quote:

Originally Posted by Ygor

Try...

Code:

nawk 'c-->0;$0~s{if(b)for(c=b+1;c>1;c--)print r[(NR-c+1)%b];print;c=a}b{r[NR%b]=$0}' b=2 a=4 s="string" file1

...where "b" and "a" are the number of lines to print before and after string "s".

Perfect!!.. This is what I was looking for. Thanks!

uttamhoode · #10 (**permalink**) 02-02-2009

awesome!!!

anduzzi · #11 (**permalink**) 02-18-2009

nawk 'c-->0;$0~s{if(b)for(c=b+1;c>1;c--)print r[(NR-c+1)%b];print;c=a}b{r[NR%b]=$0}' b=2 a=4 s="string" file1

This one liner really helped me to get what I want but there is little deviant to my problem...

I want to search for a string and go back several lines(the number of lines is not fixed) and catch a pattern which is associated with the searched string.
for eg:
<HEADER>
line1
line2
line3
line4
............
<string>
I want to somehow associate <HEADER> line once I find my <string> and discard the rest of results..As I said, the number of lines is not fixed till we traverse back to <HEADER> line.

Is there any way we can achieve this?.

-Anduzzi

Ygor · #12 (**permalink**) 02-18-2009

Try...

Code:

awk '$0~s,$0~t' s="<HEADER>" t="<string>" file1

anduzzi · #13 (**permalink**) 02-19-2009

Could you please explain the command and for some reason the syntax doesnt quite work for me ?.

Thx !

Ygor · #14 (**permalink**) 02-19-2009

http://people.cs.uu.nl/piet/docs/naw..._51.html#SEC54

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