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reverse search a text file from a specified line

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# 8  
Old 08-28-2008
further clarification
Thanks for the awk command - it works!, but not entirely. Smilie

Consider my input file parts.txt as follows.
1 useless line....
2 useless line....
3 useless line....
4 PROCESSING PART 111
5 useless line....
6 useless line....
7 ERROR processing part!
8 useless line....
9 useless line....
10 PROCESSING PART 222
11 useless line....
12 useless line....
13 useless line....
14 useless line....
15 SUCCESS!
16 PROCESSING PART 333
17 useless line....
18 useless line....
19 SUCCESS!
20 PROCESSING PART 444
21 useless line....
22 useless line....
23 ERROR processing part!
24 PROCESSING PART 555
25 useless line....
26 useless line....
27 SUCCESS!
28 useless line....
29 useless line....
30 useless line....
31 useless line....
I am looking for PART with ERROR in a pair. So my expected output should be as follows.
7 ERROR processing part!
4 PROCESSING PART 111
23 ERROR processing part!
20 PROCESSING PART 444
Running the suggested awk command returned the SUCCESS PARTs also. See below.
awk '/ERROR/ { lastb=$0 } /PROCESSING/ { print; print lastb; lastb="" }' parts.txt
4 PROCESSING PART 111

10 PROCESSING PART 222
7 ERROR processing part!
16 PROCESSING PART 333

20 PROCESSING PART 444

24 PROCESSING PART 555
23 ERROR processing part!
I only need the first occurence of the PART number in the reverse from the line where 'ERROR' is found.

Thanks.
# 9  
Old 08-28-2008
You seem to have mixed up the A and the B on your side. You should collect the PROCESSING and print when you see ERROR, shouldn't you?
# 10  
Old 08-28-2008
Quote:
Originally Posted by era
You seem to have mixed up the A and the B on your side. You should collect the PROCESSING and print when you see ERROR, shouldn't you?
Sorry for my reverse logic. But I was trying to avoid some of the intermediate 'PROCESSING' lines that I dont need to report.
# 11  
Old 08-28-2008
Code:
vnix$ awk '/PROCESSING/ { lastb=$0 } /ERROR/ { print lastb; print; lastb="" }' <<HERE
> 1 useless line....
> 2 useless line....
> 3 useless line....
> 4 PROCESSING PART 111
> 5 useless line....
> 6 useless line....
> 7 ERROR processing part!
> 8 useless line....
> 9 useless line....
> 10 PROCESSING PART 222
> 11 useless line....
> 12 useless line....
> 13 useless line....
> 14 useless line....
> 15 SUCCESS!
> 16 PROCESSING PART 333
> 17 useless line....
> 18 useless line....
> 19 SUCCESS!
> 20 PROCESSING PART 444
> 21 useless line....
> 22 useless line....
> 23 ERROR processing part!
> 24 PROCESSING PART 555
> 25 useless line....
> 26 useless line....
> 27 SUCCESS!
> 28 useless line....
> 29 useless line....
> 30 useless line....
> 31 useless line....
> HERE
4 PROCESSING PART 111
7 ERROR processing part!
20 PROCESSING PART 444
23 ERROR processing part!

Note the minor change I made in the printing order (they would come out with the ERROR before the PROCESSING line in the original script).
# 12  
Old 08-28-2008
Quote:
Originally Posted by danmero
Code:
awk '/B/{a=$0}/A/ && a {print a;a=""}' file

a will be the last occurrence of B.
I adopted the command as follows:
awk '/ERROR/{a=$0}/PROCESSING/ && a {print a;a=""}' parts.txt
and got the following...
7 ERROR processing part!
23 ERROR processing part!
The expected result is ...
4 PROCESSING PART 111
20 PROCESSING PART 444
I dont really need the 'ERROR' lines. I was only trying to show the pairing in my example.
# 13  
Old 08-28-2008
Computer
Quote:
Originally Posted by era
Code:
vnix$ awk '/PROCESSING/ { lastb=$0 } /ERROR/ { print lastb; print; lastb="" }' <<HERE
> 1 useless line....
> 2 useless line....
> 3 useless line....
> 4 PROCESSING PART 111
> 5 useless line....
> 6 useless line....
> 7 ERROR processing part!
> 8 useless line....
> 9 useless line....
> 10 PROCESSING PART 222
> 11 useless line....
> 12 useless line....
> 13 useless line....
> 14 useless line....
> 15 SUCCESS!
> 16 PROCESSING PART 333
> 17 useless line....
> 18 useless line....
> 19 SUCCESS!
> 20 PROCESSING PART 444
> 21 useless line....
> 22 useless line....
> 23 ERROR processing part!
> 24 PROCESSING PART 555
> 25 useless line....
> 26 useless line....
> 27 SUCCESS!
> 28 useless line....
> 29 useless line....
> 30 useless line....
> 31 useless line....
> HERE
4 PROCESSING PART 111
7 ERROR processing part!
20 PROCESSING PART 444
23 ERROR processing part!

Note the minor change I made in the printing order (they would come out with the ERROR before the PROCESSING line in the original script).
Awewsome! That's so cool. Thanks. Smilie
# 14  
Old 08-28-2008
Quote:
Originally Posted by PacificWonder
I am looking for PART with ERROR in a pair. So my expected output should be as follows.
7 ERROR processing part!
4 PROCESSING PART 111
23 ERROR processing part!
20 PROCESSING PART 444
Code:
awk '/PROCESSING/{a=$0} /ERROR/ && a {printf "%s\n%\s\n", $0, a ;a=""}' file

Please learn howto use the code tags, and try to provide the input sample and expected results sample from the beginning.

Regards,
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