awk text editing


 
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# 1  
Old 06-25-2014
Question awk text editing

Dear all,

I'm starting to learn programming, and I'm having some problem with awk text editing.

I'm having a huge text file, and my goal is to print "something" before every 4th row starting from the second row.

File example:
Code:
AAAAA
BBBBBB
CCCCC
DDDDD
AAAAAAA
BBBBBBBB
CCCCCCC
DDDDDDD
AAAAAAAAA
BBBBBBBBBB
CCCCCCCCC
DDDDDDDDD
etc.

The desired output would be the following:
Code:
AAAAA
XXXXXBBBBBB
CCCCC
DDDDD
AAAAAAA
XXXXXBBBBBBBB
CCCCCCC
DDDDDDD
AAAAAAAAA
XXXXXBBBBBBBB
CCCCCCCCC
DDDDDDDDD
etc.

I have written an awk one liner, but its not working, it only print the wanted letters before to the last BBB.

This is what i ran in command line:
Code:
b=`wc -l input.txt | awk '{print $1}'`; for ((i=2; i<=$b ; i+=4)); do awk -v i=$i '{if (NR==i) print "NANE"$0; else print $0}' input.txt > output.txt; done

I would really appreciate your help!

Thanks,
Higgo

Last edited by Scrutinizer; 06-25-2014 at 04:18 AM.. Reason: CODE tags
# 2  
Old 06-25-2014
Hi, in awk you can use the mod operator for this:
Code:
awk '!((NR-2)%4){$0=s $0}1' s=NANE file

Or sed:
Code:
sed '1n;s/^/NANE/;N;N;N' file

or GNU sed:
Code:
sed '2~4s/^/NANE/' file


Last edited by Scrutinizer; 06-25-2014 at 04:30 AM..
# 3  
Old 06-25-2014
Thank you! So much easier! Smilie
 
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