Ooh, that would be very useful for pack

Correction to something I said earlier -- macOS Catalina (the recently released version, earlier this month) does still include /usr/bin/ruby, perl, and python executables installed by default. I checked by installing it on one of my Macs in the house. Apple has announced that the next major release will not include them in the base macOS installation.

I will soon be installing Homebrew on it, and brew install clojure, to see if it works for me.

After installing a Java executable (I chose AdoptOpenJDK 11) and Xcode, and Homebrew, brew install clojure produced a working clojure command install on my macOS Catalina system. There is no need that I can see to change the install.sh script to make it work on that OS.

It isn't clear to me why someone earlier had a problem there, unless perhaps /usr/bin wasn't in their path so that /usr/bin/ruby was not found, but that seems unlikely to be the reason.

@andy.fingerhut if you mean me by someone earlier with macOS catalina: this was due to truffleruby (from graalvm) being used to run the install.sh script. and truffle ruby doesn’t support the -p flag yet: https://clojurians.slack.com/archives/C6QH853H8/p1571657798259600

So at the time you tried upgrading the clojure package using brew upgrade clojure, you had a ruby executable in your command PATH that was earlier than /usr/bin/ruby? If so, the results you got makes sense to me.