[morsch]

the idea is to use 'find' if you want something fancy

I don't get it, can someone explain? It also appears in the ML thread linked elsewhere, and I don't understand it there either. (I understand the reasons for the change in behaviour, just not this specific line.)

[bluetech]

find is essentially the command line tool for traversing the file system hierarchy recursively. It's got a million options, e.g. whether to follow symlinks, depth, file/directory/device/.., user, group, change time and many more. When you use grep -r, it only does the most common thing which is to just go over all the files. If you want something more "fancy", you can use find, e.g.:

  $ find -name '*.c' -type f -exec grep printf '{}' +