#!/bin/bash
# envr [PID] - print environment changes, recursively

set -e

penv() {
	sort -z /proc/$1/environ 2>/dev/null || printf "%s\n" -
}

iter() {
	local me=$1
	local parent="$(ps -h -o ppid -p $me | tr -cd 0-9)"
	if [ "$parent" -gt 0 ] && [ "$parent" -ne "$me" ]; then
		iter $parent
		echo
		ps h -F -p $me
		comm -13 -z <(penv $parent) <(penv $me) |
			tr '\0' '\n' | sed 's/^/  /'
	else
		ps -F -p $me
		penv $me | tr '\0' '\n' | sed 's/^/  /'
	fi
}

iter ${1:-$$}