Set zsh (zshell) prompt in Mac OS Catalina terminal

Catalina uses zsh (zshell) instead of the old bash or (even older) sh. To set the command prompt, modify ~/.zprofile or ~/.zshrc with something like:

#--------------------ZSH script commands--------------------#
#  %B  Bold on
#  %b  bold off
#  %F  color on, %F{green} or %F{2}
#  %f  color off
#  %D  date with strftime options in {}
#      %a  weekday 3-letter abbreviation (Mon)
#      %x  locale date (09/30/13)
#      %X  locale time (07:06:05)
#  %n  user
#  %m  machine
#  %/  directory path
#  %#  show % unless elevated privileges (sudo), then show #
#  $'\n'  newline
#
#-----------------------------------------------------------#

PROMPT="%B%F{green}%D{%a %x %X} %F{red}%n%F{white}@%F{cyan}%m %F{yellow}%/%f %#"$'\n'"> "

This will generate a prompt that looks like this, with the command prompt on the next line down:

You can use either PS1 or PROMPT. PS1 may be set in /etc/zshrc and it will override your setting. To disable it, edit /etc/zshrc and comment out the PS1 line. You may have to use sudo vim and write your changes with w! (and exit with q!) because the permissions may be set to read-only for everyone.

For a detailed explanation of setting the prompt in zsh, see:

zsh Prompt Expansion
Customizing the zsh prompt

For a list of 256 colors whose numeric values you can use in place of red, green, yellow, blue, magenta, cyan, and white, see:

256 Colors Cheat Sheet

Here's a strftime reference for options to include with %D for date and time formatting:

Python's strftime directives