How to get diff to report summary of new, changed and deleted lines

Question

I want to have summary of difference between two files. Expected output is count of new, deleted and changed lines. Does diff readily provides such output? If not is there any s

Answer 1

If you use diff -u it will generate a unified diff that has lines preceded with + and -. If you pipe that output through grep (to get only the + or -) and then to wc you get the counts for the + es and the - es respectively.