Diff command with file type exceptions

Question

While comparing 2 fairly big directories using diff -rq ... I want to exclude certain file types like tar.gz or error_log.

How do I do that?

Answer 1

GNU diff has options for doing this (see manual page):

 -x, --exclude=PAT
 exclude files that match PAT
 -X, --exclude-from=FILE
 exclude files that match any pattern in FILE

The pattern in each case is a glob (* for any number of characters):

diff -rq -x '*.tar.gz' -x '*error_log' foo bar

See for example:

• How do you diff a directory for only files of a specific type?
• How can I make 'diff -X' ignore specific paths and not file names?