https://explainshell.com is a delightful tool that you can link to in conjunction with the shell one-liners that you paste to friends and colleagues to help them understand what your gibberish actually does.

Bash uses the Extended Regular Expression (ERE) dialect. See http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04 for details.

• https://delx.net.au/blog/2016/03/safe-bash-scripting-set-e-is-not-enough/

exec 19> ~/"${BASH_SOURCE[0]##*/}.xtrace.log"
export BASH_XTRACEFD=19
export PS4='+ $$($BASHPID) +${SECONDS}s (${BASH_SOURCE[0]}:${LINENO}): ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'
set -vxueo pipefail

SSH_CLIENT="${SSH_CLIENT:-}"
SSH_CONNECTION="${SSH_CONNECTION:-}"
SSH_TTY="${SSH_TTY:-}"
PROG="${0##*/}"

• How to create simple Mac apps from shell scripts