How to get and extract filename extension in Bash https://www.cyberciti.biz/faq/extract-bash-get-filename-extension/
Discussion
nostr:npub1gfdrrw9629qxwvwaa3vwnvzhtaqu2c5m9wf6vcwjnmdnhs7hl4jsux7gg6 Fails if there are multiple dots in the filename. For instance, "this.is.a.test.avi"