I am on MacOS Cagalina 10.15.4. I thought mapfile and readarray are available with Bash 4 and later but got below. May I ask what I am doing wrong?
$ brew install bash
$ bash --version
GNU bash, version 5.0.17(1)-release (x86_64-apple-darwin19.4.0)
Copyright (C) 2019 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
$ mapfile
-bash: mapfile: command not found
$ readarray
-bash: readarray: command not found