I have many nested folders of json language files, such as

```
da-dk.json
de-de.json
en-us.json

```

I need to change them all to capitalize the letters after the hyphen, as in

```
da-DK.json
de-DE.json
en-US.json

```

I am on a Mac with zsh. I originally thought I could do it with a GUI utility I have used called A Better Finder Rename but it apparently does not offer case conversions on replace.

I know regex and figured it would be something like find
`^([a-z]{2})-([a-z]{2})` and replace with `$1-\U$2` but I'm not sure how to do this in the command line.