Compare two files and print unmatched lines [duplicate]

Question

I have two files with the below data; I need the difference between two files.

I tried with diff but it also shows line which are common in the two files: (22372 Dec 4 15:36 /opt/apache-tomcat-6.0.36/webapps/new/new.txt).

First file: (multiple data exists in the same way in file 1)

22677 Dec 4 15:36 /opt/apache-tomcat-6.0.36/webapps/new/abc.txt

22372 Dec 4 15:36 /opt/apache-tomcat-6.0.36/webapps/new/new.txt

Second file: (multiple data exists in the same way in file 2).

22372 Dec 4 15:36 /opt/apache-tomcat-6.0.36/webapps/new/new.txt

22677 Dec 3 15:36 /opt/apache-tomcat-6.0.36/webapps/new/abc.txt

12344 Dec 10 15:36 /opt/apache-tomcat-6.0.36/webapps/abc/.../test.txt

I need the below output:

22677 Dec 3 15:36 /opt/apache-tomcat-6.0.36/webapps/new/abc.txt

12344 Dec 10 15:36 /opt/apache-tomcat-6.0.36/webapps/abc/.../test.txt

Answer 1

This seems like a perfect opportunity to use comm.

From the GNU coreutils manual page (v8.30):

With  no  options,  produce  three-column  output.  Column one contains
lines unique to FILE1, column two contains lines unique to  FILE2,  and
   column three contains lines common to both files.

   -1     suppress column 1 (lines unique to FILE1)

   -2     suppress column 2 (lines unique to FILE2)

   -3     suppress column 3 (lines that appear in both files)

Using this information, we can remove the lines unique file1 as well as the lines present in both files.

$ comm -1 -3 <(sort file1) <(sort file2)
12344 Dec 10 15:36 /opt/apache-tomcat-6.0.36/webapps/abc/.../test.txt
22677 Dec 3 15:36 /opt/apache-tomcat-6.0.36/webapps/new/abc.txt

-1 and -3 removes all lines unique to file 1 and all lines common to both.

Because of the sort, it will change the order of the output but that doesn't seem to be a consideration based on the question.

If the input is already sorted, you can skip the sorts yielding

$ comm -1 -3 file1 file2

Answer 2

Use diff -u file1 file2 | sed -nr 's/^+([^+].*)/\1/p'

Output:

22677 Dec 3 15:36 /opt/apache-tomcat-6.0.36/webapps/new/abc.txt
12344 Dec 10 15:36 /opt/apache-tomcat-6.0.36/webapps/abc/.../test.txt

If you need the blank line between them, use
diff -u file1 file2 | sed -nr 's/^+([^+].*)/\1\n/p'

Output:

22677 Dec 3 15:36 /opt/apache-tomcat-6.0.36/webapps/new/abc.txt

12344 Dec 10 15:36 /opt/apache-tomcat-6.0.36/webapps/abc/.../test.txt