Subject: mention that diff -s shows more than just identical files

From: 積丹尼 Dan Jacobson <[email-masked]>
Date: Tue, 26 Dec 2017 19:40:53 +0800

In (info "(diffutils) Comparing Directories")

"Normally 'diff' is silent about pairs of files that contain
no differences, but if you use the '--report-identical-files' ('-s')
option, it reports pairs of identical files."

OK, but add: To see ONLY the identical files, use
$ diff --recursive --brief --report-identical-files tree1 tree2 | grep identical$