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Search backwards to certain string

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# 8  
Old 03-26-2012
Hi.

I'm still not confident that I understand your question, so perhaps these meta-answers may help.

There was a suggested solution from balajesuri in perl that you may have missed. I don't know about the definite timing of the reading-backwards module, and you seem to not be able to install items, but I think that module might be standard. (The sample code I tried in 2010 was almost instantaneous, but that was with a very short file.) If you do not have it, there are other solutions.

Assuming that the suggestion from birei is correct, you could try various means for reversing a file.

You may not have tac or rev, but there are versions available in perl from one of the CPAN projects.

So you could try using any of those:
PPT: tac
( link to rev removed )

Other approaches to producing a reverse copy of a file are, one in sed:
Code:
sed -n '1{
h
}
1 !{
x
H
}
${
x
H
p
}' inputfile

and you could also add line numbers (cat -n), sort in reverse, and remove the line numbers (cut) to get a reverse copy of a file.

Best wishes ... cheers, drl
Last edited by drl; 03-26-2012 at 12:41 PM.. Reason: Removed link to perl rev, it reverses characters on lines.
This User Gave Thanks to drl For This Post:
SaltyDog
# 9  
Old 03-26-2012
Quote:
Originally Posted by SaltyDog
Unfortunately we don't have ruby/glark/tac etc installed which is why I was looking towards an sed/awk solution.


corresponding to the previous policy reference before the "CS95869005 No BC record found. Please review urgently" line
............
Code:
# cat data
..............
....
.......
................
....................
CS02010002 Policy "9999998599"
CS13000008 Tax processing was done for 17/03/2012.
..............
....
.......
................
....................
....................
....................
.......................................
CS95869005 No BC1 record found. Please review urgently

========================================================
CS02010002 Policy 9999998599
SS00200001 Change of adress processed
CS13000008 Tax processing was done for 18/03/2012.
CS02010002 Policy 9999999609
CS02010002 Policy 9999999619
CS02010002 Policy 9999999629
CS43500005 Payout Number A0002 is being processed now.
CS43500005 Payout Number A0003 is being processed now.
CS02010002 Policy 9999999639
CS43500005 Payout Number A0001 is being processed now.
CS02010002 Policy 9999999759
========================================================

CS02010002 Policy "9999999899"
....
.......
....
.......
..............
CS43500005 Payout Number A0003 is being processed now.
CS13000008 Tax processing was done for 17/03/2012.
CS95869005 No BC2 record found. Please review urgently
....
.......
....
.......
..............

Code:
# awk -vstart='CS02010002' -vfstop="No BC" -vlstop=" record found. Please review urgently" '
{while(getline){if($0~start)policy=$3;if($0~fstop "[0-9]*" lstop)print policy}}' data
"9999998599"
"9999999899"

This User Gave Thanks to ygemici For This Post:
SaltyDog
# 10  
Old 03-27-2012
Quote:
Code:
# awk -vstart='CS02010002' -vfstop="No BC" -vlstop=" record found. Please review urgently" '
{while(getline){if($0~start)policy=$3;if($0~fstop "[0-9]*" lstop)print policy}}' data
"9999998599"
"9999999899"

This is exactly what I was looking for but I can't get it working. I tried the above and then amended it slightly to the following

Code:
awk -v start='CS02010002' -v fstop="CS95869005"  '{while(getline){if($0~start)policy=$3;if($0~fstop)print policy}}'  FILE

but this just gives me


Code:
awk: syntax error near line 1
awk: bailing out near line 1

# 11  
Old 03-27-2012
On Solaris use /usr/xpg4/bin/awk or nawk... Otherwise try this:

Code:
awk '$2=="Policy"{p=$3}$0~s{print p}' s=CS95869005 infile

or for example:

Code:
awk '$2=="Policy"{p=$3}$0~s{print p}' s="No BC record found" infile

This User Gave Thanks to Scrutinizer For This Post:
SaltyDog
# 12  
Old 03-27-2012
A completely different approach, but unsuitable for very large files because it does an extra pass of the file for each error found.
Works by numbering the lines in the input stream, finding each occurance of "No BC record found" and then scanning the ten lines above that record for the last occurrence of a record containing "Policy".

Code:
cat -n filename.txt | grep "No BC record found"|awk '{print $1}' | while read E1
do
        # Line ten lines above "No BC record found"
        E2=$((${E1} - 10))
        if [ ${E2} -le 0 ]
        then
                E2=1
        fi
        # Line number one line above "No BC record found"
        E3=$((E1 -1))
        # Search 10 line block to just above "No BC record found"
        sed -n "${E2},${E3}p;${E3}q" filename.txt | \
                grep "Policy" | tail -1 | awk '{print $3}'
done

./scriptname
9999998599
9999999899

... and I know that it has a "cat" command in it !
Last edited by methyl; 03-27-2012 at 01:16 PM.. Reason: spellin
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