Given two directory trees, how can I find out which files differ by content? [closed]

Question

If I want find the differences between two directory trees, I usually just execute:

diff -r dir1/ dir2/ 

This outputs exactly what the differences are between corresponding files. I'm interested in just getting a list of corresponding files whose content differs. I assumed that this would simply be a matter of passing a command line option to diff, but I couldn't find anything on the man page.

Any suggestions?

Answer 1

Try:

diff --brief --recursive dir1/ dir2/ 

Or alternatively, with the short flags -qr:

diff -qr dir1/ dir2/ 

If you also want to see differences for files that may not exist in either directory:

diff --brief --recursive --new-file dir1/ dir2/  # with long options diff -qrN dir1/ dir2/                            # with short flag aliases 

Answer 2

The command I use is:

diff -qr dir1/ dir2/ 

It is exactly the same as Mark's :) But his answer bothered me as it uses different types of flags, and it made me look twice. Using Mark's more verbose flags it would be:

diff  --brief --recursive dir1/ dir2/ 

_{I apologise for posting when the other answer is perfectly acceptable. Could not stop myself... working on being less pedantic.}