[SOLVED] Comparing files in bash script

brainlesseinstein · 09-02-2010, 02:49 AM

Hello,

I want to compare two files and display values unique to file1. I tried using comm but it did not give me useful outputs.

comm -2 -3 file1 file2 does not work

Similar threads provide matched content. What I am looking for is unique content

grail · 09-02-2010, 02:55 AM

How about diff?

brainlesseinstein · 09-02-2010, 03:02 AM

Diff performs a line by line check whereas situation can be as following:

file1
1
2
3
4
5

file2
4
3
2
5

I need the output to be 1 because it is unique to file1. Whereas diff performs a line by line search and gives the following result

diff file1 file2
1,4d0
< 1
< 2
< 3
< 4
5a2,4
> 4
> 3
> 2

druuna · 09-02-2010, 03:10 AM

Hi,

Both comm and diff only work on sorted files.

If you sort file 2 then comm -23 file1 file2 will give you the answer you are looking for.

Hope this clears things up a bit.

repo · 09-02-2010, 03:19 AM

How about using the option

Code:

comm file-1 file-2 outputs three columns:
column 1 = lines unique to file-1
column 2 = lines unique to file-2
column 3 = lines common to both.

-1 suppresses column 1
-2 suppresses column 2
-3 suppresses column 3
-12 suppresses both columns 1 and 2, etc.

Code:

comm -23 file1 file2

See man com
Kind regards

druuna · 09-02-2010, 03:26 AM

@repo: The OP's command given in the initial post works _if_ both files are sorted. I don't see how your comment solves the unsorted input file(s), I do think s/he looked at the man page to come up with: comm -2 -3 file1 file2

repo · 09-02-2010, 03:29 AM

Quote:

Originally Posted by druuna

@repo: The OP's command given in the initial post works _if_ both files are sorted. I don't see how your comment solves the unsorted input file(s), I do think s/he looked at the man page to come up with: comm -2 -3 file1 file2

Correct

brainlesseinstein · 09-02-2010, 03:45 AM

Thanks druuna ... this was the missing link

I was using it on unsorted files

druuna · 09-02-2010, 03:45 AM

You're welcome

makyo · 09-02-2010, 12:41 PM

Hi.

I often find it irritating to need to sort files for comm, join, etc. One can write scripts to that, of course. However, occasionally, there exists a utility that is designed to handle such situations. In this case command combine can do this. For your data on files data1 and data2:

Code:

combine data1 not data2

produces:

Code:

The command combine was found in package moreutils in the Debian 5 ("lenny") repository, and the latter can also be found at
http://kitenet.net/~joey/code/moreutils/

A quick glance with zypper on openSUSE 11.3 "Teal" did not find it, but yum on Fedora release 13 (Goddard) did find it. Don't confuse it with perl module List::MoreUtils.

Best wishes ... cheers, makyo

The environment was:

Code:

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0 
GNU bash 3.2.39
combine - ( /usr/bin/combine Jun 28 2008 )