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Compare large file and identify difference in separate file

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# 1  
Old 03-15-2012
Compare large file and identify difference in separate file
I have a very large system generated file containing around 500K rows size 100MB like following
Code:
  
  HOME|ALICE STREET|3||NEW LISTING
  HOME|NEWPORT STREET|1||NEW LISTING
  HOME|KING STREET|5||NEW LISTING
  HOME|WINSOME AVENUE|4||MODIFICATION
  CAR|TOYOTA|4||NEW LISTING
  CAR|FORD|4||NEW LISTING
  COMPUTER|HP|1||NEW LISTING
  COMPUTER|APPLE|1||NEW LISTING

The file is generated once a day. Everyday some rows are deleted some modified and some added as following (Line 2 in first file is deleted, Line 5 in first file is modified and Line 6 in second file is added)
Code:
   
  HOME|ALICE STREET|3||NEW LISTING
  HOME|KING STREET|5||NEW LISTING
  HOME|WINSOME AVENUE|4||MODIFICATION
  CAR|TOYOTA|5||NEW LISTING
  CAR|FORD|4||NEW LISTING
  CAR|HONDA|4||NEW LISTING
  COMPUTER|HP|1||NEW LISTING
  COMPUTER|APPLE|1||NEW LISTING

I want to identify those rows deleted into a file and those rows modified and added into a file.

Diif File 1 should be
Code:
 
  HOME|NEWPORT STREET|1||NEW LISTING

And Diff File 2 should be
Code:
   
  CAR|TOYOTA|5||NEW LISTING
  CAR|HONDA|4||NEW LISTING

I am very new to shell scripting. Any help is very much appreciated.

Moderator's Comments:
Mod Comment Please use next time code tags for your code and data
# 2  
Old 03-15-2012
Take a look at the output of
Code:
diff file1 file2

# 3  
Old 03-15-2012
I don't think that the output format from "diff" is suitable and it tends to get lost on large unsorted files.


The file must be a proper unix text file. In your sample, the data has no particular sorted order.

You'll need to "sort" both files to produce two new sorted output files in a work area. Then compare the two sorted files using two different unix "comm" commands. The differences will not be in the same order as the original file.
# 4  
Old 03-15-2012
Hi.

I think I would still try GNU diff first. If it works, then you are done, if not, then something else can be tried, such as the suggestion from methyl.

If your files are described as:
Code:
   When the files you are comparing are large and have small groups of
changes scattered throughout them, you can use the
`--speed-large-files' option to make a different modification to the
algorithm that `diff' uses.  If the input files have a constant small
density of changes, this option speeds up the comparisons without
changing the output.  If not, `diff' might produce a larger set of
differences; however, the output will still be correct.

-- excerpt from info diff, q.v.

then you may want to experiment with that.

Best wishes ... cheers, drl
# 5  
Old 03-20-2012
I am basically trying to identify the deleted rows from first file.
Code:
$ cat file1
HOME|ALICE STREET|3||NEW LISTING
HOME|NEWPORT STREET|1||NEW LISTING
HOME|KING STREET|5||NEW LISTING
HOME|WINSOME AVENUE|4||MODIFICATION
CAR|TOYOTA|4||NEW LISTING
CAR|FORD|4||NEW LISTING
COMPUTER|HP|1||NEW LISTING
COMPUTER|APPLE|1||NEW LISTING
$ cat file2
HOME|ALICE STREET|3||NEW LISTING
HOME|KING STREET|5||NEW LISTING
HOME|WINSOME AVENUE|4||MODIFICATION
CAR|TOYOTA|5||NEW LISTING
CAR|FORD|4||NEW LISTING
CAR|HONDA|4||NEW LISTING
COMPUTER|HP|1||NEW LISTING
COMPUTER|APPLE|1||NEW LISTING
$ diff file1 file2
2d1
< HOME|NEWPORT STREET|1||NEW LISTING
5c4
< CAR|TOYOTA|4||NEW LISTING
---
> CAR|TOYOTA|5||NEW LISTING
6a6
> CAR|HONDA|4||NEW LISTING
$


I am trying to get a output file containing only deleted line from first file, in this instance following
Code:
HOME|NEWPORT STREET|1||NEW LISTING

Last edited by Franklin52; 03-20-2012 at 04:54 AM.. Reason: Please use code tags for code and data samples, thank you
# 6  
Old 03-20-2012
try this,
Code:
 
awk 'NR==FNR{a[$0]++;next} !a[$0]' file2 file1

# 7  
Old 03-20-2012
awk
Hi,

Try this one, It will consider the first 2 columns as a key. Just little modification from pravin's post.

Code:
awk 'BEGIN{FS="|";}NR==FNR{a[$1$2]++;next}!a[$1$2]' file2 file1

Output:
Code:
HOME|NEWPORT STREET|1||NEW LISTING

Cheers,
RangaSmilie
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