Printing a stack trace in bash

trap_test.sh

#!/bin/bash

fatal() {
  local frame=0
  while caller $frame; do
    ((frame++));
  done
  echo "$*"
  exit 1
}

f1(){
  undefined_command
  if [ $? -ne 0 ]; then
    fatal "things went bad."
  fi
}
f2(){
  f1
}
f3(){
  f2
}
f3