Question

I am trying to use comm to compute the difference between two sorted files, however the result doesn’t make sense, what’s wrong? I want to show the strings that exists in test2 but not test1, and then show the strings that exist in test1 but not test2

>test1
a
b
d
g

>test2
e
g 
k
p

>comm test1 test2
a
b
d
    e
g
    g 
    k
    p

Answer 1

To show the lines that exist in test2 but not in test1, write either of these:

comm -13 test1 test2
comm -23 test2 test1

(-1 hides the column with lines that exist only in the first file; -2 hides the column with lines that exist only in the second file; -3 hides the column with lines that exist in both files.)

And, vice versa to show the lines that exist in test1 but not in test2.

Note that g on a line by itself is considered distinct from g with a space after it, which is why you get

g
    g 

instead of

        g