How do I do a one way diff in Linux?

Question

How do I do a one way diff in Linux?

Normal behavior of diff:

Normally, diff will tell you all the differences between a two files. For e

Answer 1

As stated in the comments, one mostly correct answer is

diff A B | grep '^<'

although this would give the output

< good dog
< two

rather than

2c2
< good dog
4c4,5
< two