#! /bin/sh
set -euf

pid=$$
while :; do
  cd /proc/$pid
  cmdline=$(cat cmdline | sed 's/\0/ /g;s/ $//')
  ppid=$(grep PPid status | awk '{print$2}')
  printf '%5d %s\n' $pid "$cmdline"
  if [ $pid = 1 ]; then
    break
  else
    pid=$ppid
  fi
done \
  | tac