Script to produce a bash stacktrace, compatible with Bash v5.x

stacktrace.sh

function stacktrace() {
  if ! command -v realpath > /dev/null 2>&1; then
    function realpath() {
      cd "${1}" > /dev/null 2>&1 && pwd || printf "?"
    }
  fi

  printf "Script stacktrace (most recent call first):\n"

  local frame=0
  local line func file

  while read -r line func file < <(caller "${frame}"); do
    printf "\t%s:%s (file=%s)\n" "${func}" "${line}" "${file}"
    ((frame = frame + 1))
  done

  printf "Process hierarchy (child processes first):\n"

  local pid=$$
  local exe cwd

  while [[ -d /proc/${pid} ]]; do
    exe=$(cut -d $'\0' -f2 "/proc/${pid}/cmdline")
    cwd=$(realpath "/proc/${pid}/cwd")
    printf "\t%s (pid=%s, cwd=%s)\n" "${exe}" "${pid}" "${cwd}"
    if ((pid <= 1)); then
      # Root process, so we cannot go any further.
      break
    else
      pid=$(cut -d ' ' -f4 "/proc/${pid}/stat")
    fi
  done
}

# If the script was invoked directly rather than sourced, generate
# some demo output.
if ! (return > /dev/null 2>&1); then
  function __stacktrace_demo() {
    function func1() { func2; }
    function func2() { func3; }
    function func3() { func4; }
    function func4() { func5; }
    function func5() { stacktrace; }
    func1
  }
  __stacktrace_demo
fi