Supposedly, macOS 10.15 Catalina is slated to replace the default /bin/bash shell with zsh, or /bin/zsh. Before we talk about the differences let’s just say that bash is still here and if your script is called as bash then it will still work just fine. To quickly see which you’re using (e.g. when testing a new release), use $0: echo $0 Z Shell or zsh for short was written by Princeton University student Paul Falstad in 1990. Most shells are just extensions of the Bourne shell (including bash) and work similarly but there are minor differences here and there. Yes, Z Shell comes with a control-R reverse incremental search, but…