Grepping text block by block by using for loop


 
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# 1  
Old 09-24-2012
Grepping text block by block by using for loop

Hei buddies,
Need ur help once again.

I have a file which has bunch of lines which starts from a fixed pattern and ends with another fixed pattern.
I want to make use of these fixed starting and ending patterns to select the bunch, one at a time.

The input file is as follows.
Code:
Hi welcome
blah blah blah
blah blah blah
Bye**
Hi welcome
blah  blah
blah  blah
blah  blah
blah  blah
blah  blah
Bye**
Hi welcome
blah 
blah 
Bye**
Hi welcome
blah blah blah
blah blah blah
blah blah blah
blah blah blah
blah blah blah
Bye**
Hi welcome
blah blah blah
Bye**

I tried using awk '/Hi welcome/,/Bye**/' inputfile.txt to select text from Hi welcome to Bye** However, it selects complete document may be because even whole document starts with "Hi welcome" and ends with "Bye**". Here I am trying to get it block by block (From Hi welcome to Bye** is one block) in a temp file by using for loop.

Please help. Little urgent.

Thank you.
Anu.

Last edited by Scrutinizer; 09-24-2012 at 07:58 AM.. Reason: code tags
# 2  
Old 09-24-2012
Try this....

Code:
awk '{if($0 ~ /^Hi welcome/){ s=$0}else{if($0 !~ /Bye\*\*/){if(s != "") { s=s"\n"$0}}else{s=s"\n"$0; print s"\n"}}}' file > temp_file

# 3  
Old 09-24-2012
Hi Pamu,
The solution is not working. Output file is generated of zero MB :-(
# 4  
Old 09-24-2012
Quote:
Originally Posted by anushree.a
The solution is not working. Output file is generated of zero MB :-(
What is output of this..?

Code:
awk '{if($0 ~ /^Hi welcome/){ s=$0}else{if($0 !~ /Bye\*\*/){if(s != "") { s=s"\n"$0}}else{s=s"\n"$0; print s"\n"}}}' file

# 5  
Old 09-24-2012
I don't think you can use awk to process parts of files in a loop, at least not without additional measures. Try this suggestion to create several .tmp files that you can loop through afterwards:
Code:
awk     '/^Hi welcome/ {++fn}
         {print >fn".tmp"}   
         /Bye\*\*/ {close (fn".tmp")}
        ' infile

You could even leave out the /Bye.../ line if there's not too many files open...
# 6  
Old 09-24-2012
Hi Pamu, once i pressed "Enter" key it returned to $ prompt without giving any output on screen.

Hi Rudic, the solution that you have given is working fine but :-( I have more than a million records ka file to process. So its difficult to follow your suggestion. Any better way of doing it.

Please help
Anu.
# 7  
Old 09-24-2012
Well, here's a solution to use in a for loop (in bash!). It will not be too performant on large files, as awk always scans through the entire file!
Code:
for ((i=1;i<=5;i++))
do
echo Block: $i
awk     '/^Hi welcome/ {++fn}
     {if (fn==blockno) print}
    ' blockno=$i test
done

Redirect the output if you're happy with the result.
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