comm command not comparing words

Question

I am trying to learn shell programming and for that I am using ubuntu app in windows 10, I read about the comm command and as I have understood it it should be working as below

file1.txt    file2.txt
abc          abc
cde          efg
a            b
b            c

the result should be
a
cde
             abc
             b
      c
      efg

but what I am getting is

abc
a
cde            
              b
       efg
       abc
       c

this is how I used the command

comm file1.txt file2.txt

I suspect its because I am using it on a windows app but other commands such as grep uniq ps pwd... all are working fine Any help would be appreciated

Answer 1

Windows is not the problem here. You used comm in the wrong way. man comm states

comm - compare two sorted files line by line

Therefore, you have to sort both files first.

Use

sort file1.txt > file1sorted
sort file2.txt > file2sorted
comm file1sorted file2sorted

Or if you are using bash (not plain sh or some other shell)

comm <(sort file1.txt) <(sort file2.txt)