Case 1: You know the exact file name to look for

Use find with test -e your_file to check if a file exists. For example, you look for directories which have no cover.jpg in them:

find base_dir -mindepth 2 -maxdepth 2 -type d '!' -exec test -e "{}/cover.jpg" ';' -print

It's case sensitive though.

Case 2: You want to be more flexible

You're not sure of the case, and the extension might be jPg, png...

find base_dir -mindepth 2 -maxdepth 2 -type d '!' -exec sh -c 'ls -1 "{}"|egrep -i -q "^cover.(jpg|png)$"' ';' -print

Explanation:

• You need to spawn a shell sh for each directory since piping isn't possible when using find


• ls -1 "{}" outputs just the filenames of the directory find is currently traversing


• egrep (instead of grep) uses extended regular expressions; -i makes the search case insensitive, -q makes it omit any output


• "^cover.(jpg|png)$" is the search pattern. In this example, it matches e.g. cOver.png, Cover.JPG or cover.png. The . must be escaped otherwise it means that it matches any character. ^ marks the start of the line, $ its end

Other search pattern examples for egrep:

Substitute the egrep -i -q "^cover.(jpg|png)$" part with:

• egrep -i -q "cover.(jpg|png)$" : Also matches cd_cover.png, album_cover.JPG ...


• egrep -q "^cover.(jpg|png)$" : Matches cover.png, cover.jpg, but NOT Cover.jpg (case sensitivity is not turned off)


• egrep -iq "^(cover|front).jpg$" : matches e.g. front.jpg, Cover.JPG but not Cover.PNG

For more info on this, check out Regular Expressions.