Find 2nd level directories without files with a certain extension

I have a lot of directories and subdirectories like:

abc/123/

abc/456/

def/789/

Some of them have jpeg files on them:

abc/123/

abc/456/foo.jpg

abc/456/bar.jpg

def/789/foo.jpg

I want to find the one that are missing a jpg

Learning from here I was able to get what I wanted with:

find . -mindepth 2 -maxdepth 2 -type d ‘!’ -exec sh -c ‘ls -l “{}”|egrep -i -q “*\.jpg$”‘ ‘;’ -print

How to rename file extensions recursively

The rename utility can’t be used recursively, only for file names in the current directory.

Instead, we can combine rename and find like this:

find . -name '*.jpeg' -exec rename 's/\.jpeg$/\.jpg/' {} \;

How to remove annoying tags from every srt subtitle file

Sites like opensubtitles.org have the annoying habit of tagging their files with subtitles like “Tip for download: Open Subtitles MKV Player” and “Downloaded from http://www.opensubtitles.org”.

Here is a fast single command to get rid of all that on all subrip (.srt) files, using find, sed, and a bit of regex:

find . -name \*.srt -execdir sed -i '/pen.*ubtitles/d' {} +

I did it for dozens of files in one command ;)

“find” searches all subdirectories below the current one (.) for every file with the srt extension (-name \*.srt) and executes the sed command that deletes on those files ({} +) the lines matching the regex pattern (pen.*ubtitles).