to compare two fields in two different files

Question

In file1, I have

1023M  BLD
123G   DEV
945K   Deployment
4899   INT

In file2, I have

1.2G   BLD
123G   DEV
345M   Deployment
499M   INT

I wanted to compare the first field of file1 with first field of file2. I just wanted to print only the mismatching fields in file3

Answer 1

With the sample files, below command will provide you with the needed result

$ paste file1 file2 | awk '$1!=$3'

Sample output will be as below

1023M  BLD  1.2G   BLD
945K   Deployment   345M   Deployment
4899   INT  499M   INT

use redirection to file to write this to file3.

Answer 2

If you would like to think the problem in SQL like way, then you definitely should try a tool named 'q':

$ q 'SELECT f1.*, f2.* FROM file1 f1 JOIN file2 f2 ON f1.c2 = f2.c2 WHERE f1.c1 != f2.c1';

It is more clear and easy to understand if you're familiar with SQL query.

Answer 3

I would use diff or sdiff, because i feel like it is a less hacked solution, and do some manipulation with the output with awk or a similar tool, if needed.

➜  ~  sdiff 1.txt 2.txt
1023M  BLD                 |  1.2G   BLD
123G   DEV                    123G   DEV
945K   Deployment          |  345M   Deployment
4899   INT                 |  499M   INT

Then you can see the values which differ after the pipe symbol.

Grep it off to those only, like in the above answer:

➜  ~  sdiff 1.txt 2.txt | grep '|'
1023M  BLD                 |  1.2G   BLD
945K   Deployment          |  345M   Deployment
4899   INT                 |  499M   INT

I personally think this is a more smooth solution. To redirect just do:

➜  ~  sdiff 1.txt 2.txt | grep '|' > 3.txt

You can also use diff and grep to get only the fields which differ from first line:

➜  ~  diff 1.txt 2.txt | grep "^>"
> 1.2G   BLD
> 345M   Deployment
> 499M   INT