use 'find' to search for directories !containing certain filetype foo

Question

I have a few directories, some with a depth of 3, which contain mixed file types. What I need to do is to rm -rf all the subdirectories that do not contain filetype foo.

Is this achievable with find somehow? I do know that I can use find like this:

find . ! -name '*.foo' -delete

to delete all files within the directories that do not contain any file of type *.foo. Now, how can I use this, to not only delete all unwanted files, but all directories and subdirectories which do not contain *.foo?

Answer 1

IIUYC, you can simply first remove all unwanted files using

find . ! -type f -name '*.foo' -delete

which may empty some directories. Then you can remove the empty directories (and directories containing only empty directories, etc.) like in my question

find . -depth -mindepth 1 -empty -type d -exec rmdir -p -- {} +

Answer 2

I'm not quite sure this can be done using only find, but I think we can do it using only bash and find.

tree_contains_foo_files()
{
    # return true (0) as soon as we find a "*.foo" file
    find "$1" -type f -name "*.foo" -print0 |
        read -r -d $'\0' file && return 0

    return 1
}

find . -depth -type d -print0 |
while read -r -d $'\0' dir; do
    if ! tree_contains_foo_files "$dir"; then
        rm -rf "$dir"
    fi
done

Given this test tree:

.
./dir1
./dir1/dir1.1
./dir1/dir1.1/dir1.1.1
./dir1/dir1.1/dir1.1.1/file.foo
./dir1/dir1.1/file.bar
./dir2
./dir2/dir2.1
./dir2/file.bar
./dir3

I get this result:

rm -rf ./dir2/dir2.1
rm -rf ./dir2
rm -rf ./dir3

which I think is what you want, i.e. don't delete dir1, because dir1/dir1.1/dir1.1.1 contains file.foo.

But note that it does process directories multiple times, so it might be slow for large trees. If efficiency is important, I'd use a more powerful programming language.

Answer 3

(Your question is not clear: if a directory contains some.foo and some.bar, should it be deleted? I interpreted it as requiring such a directory to be kept.)

The following script should work, provided that no file name contains a newline and no directory matches *.foo. The principle is to traverse the directory from the leaves up (-depth), and as *.foo files are encountered, the containing directory and all parents are marked as protected. Any reached file that is not *.foo and not protected is a directory to be deleted. Because of the -depth traversal order, a directory is always reached after the *.foo files that might protect it. Warning: minimally tested, remove the echo at your own risk.

find . -depth -name '*.foo' -o -type d | awk '{
    if ($0 ~ /\.foo$/) {
        while (sub("/+[^/]+$", "")) {protect[$0]=1;}
    } else {
        if (!protect[$0]) {
            gsub("[\\\001-/]", "\\\\&"); # protect file names for xargs
            print;
        }
    }
}' | xargs echo rm -rf

_{For once, I'm not proposing a zsh solution.}