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 script/utility available which helps in getting the summary.

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.

Answer 2

I think you are looking for diffstat. Simply pipe the output of diff to diffstat and you should get something like this.

 include/net/bluetooth/l2cap.h |    6 ++++++
 net/bluetooth/l2cap.c         |   18 +++++++++---------
 2 files changed, 15 insertions(+), 9 deletions(-)