diff between two strings in bash

Question

I have two strings containing lines of information. I want to obtain the lines that are different in the two strings. Example: String1:

"This is line1
This is line2
This is line3"

String2:

"This is line1
This is linex
This is line2"

Result expected:

diff string1 string2 is:
"This is line3"

diff string2 string1 is:
"This is linex"

Answer 1

You could use comm:

$ str1="This is line1
> This is line2
> This is line3"
$ str2="This is line1
> This is linex
> This is line2"

$ comm -23 <(echo "$str1" | sort) <(echo "$str2" | sort)
This is line3
$ comm -23 <(echo "$str2" | sort) <(echo "$str1" | sort)
This is linex

Answer 2

You could do smth like what you want namely with diff

$ str1="This is line1\nThis is line2\nThis is line3"; str2="This is line1\nThis is linex\nThis is line2";
$
$ diff -y -W 30 --suppress-common-lines <(echo -e $str1) <(echo -e $str2)
              > This is linex
This is line3 <

Inspired by this question&answers: Bash string difference