Find the difference between two files

Question

I have the following situation:

The file1.dat is like:

and the file2.dat is like:

I want to find the differences between the second file from the first. I tried wit grep -v -f file1 file2 but my real files are bigger than this two and when I tried with it the shell never ended is work.

The result should be:

2 3
3 4

The files are sorted and they have the same number of elements. Any way to find a solution with awk?

Possible Duplicate: http://stackoverflow.com/questions/8181974/compare-two-files-with-awk-or-sed — halex, Mar 06 '13 at 15:23
why `1 3` not in result? it is in file1, but not in file2. it is difference right? — Kent, Mar 06 '13 at 15:28

Chris Seymour · Accepted Answer · 2013-03-06T15:34:06.477

12

Seems like you want lines in file2 that are not in file1:

$ awk 'FNR==NR{a[$0];next}!($0 in a)' file1 file2
2 3
3 4

However it's simpler to use comm:

$ comm -13 file1 file2
2 3
3 4

edited Mar 06 '13 at 15:34

answered Mar 06 '13 at 15:24

Chris Seymour

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why the -13 ? what does it means? – Valerio D. Ciotti Mar 06 '13 at 16:14
4

Read `man comm` `-1` to suppress the lines unique to file one and `-3` to suppress the lines common to both.. leaving only lines unique in file2. – Chris Seymour Mar 06 '13 at 16:21
comm is a great suggestion. I used it to compare shellcode after awking distinct values – dmittakarin8 Mar 12 '15 at 16:27
@ChrisSeymour . What do I change if I want records which are missing in either of files not just file2 , Dont want to use diff but awk to get missing records along with file name . – user2854333 Dec 07 '17 at 18:49

Find the difference between two files

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