Trying to make "cont-init.d/30-init-dbus" similar to "init_dbus.sh"

30-init-dbus

#!/usr/bin/execlineb -P
# NOTE: cont-init.d/30-init-dbus
# -*- mode: bash -*-
# vi: set ft=bash:


with-contenv

trap -x
{
  term
  {
    foreground
    {

      # find location of PID_FILE
      backtick -n PID_FILE { redirfd -w 2 /dev/null find /tmp -name 'pydbustest_pid_file*' -print }
      foreground { s6-echo " [sigterm-dbus-daemon] PID_FILE:${PID_FILE}" }
      importas PID_FILE PID_FILE

      backtick -n ADDRESS_FILE { redirfd -w 2 /dev/null find /tmp -name 'pydbustest_address*' -print }
      foreground { s6-echo " [sigterm-dbus-daemon] ADDRESS_FILE:${ADDRESS_FILE}" }
      importas ADDRESS_FILE ADDRESS_FILE

      # find PID number
      backtick -n PID { redirfd -w 2 /dev/null cat ${PID_FILE} }
      foreground { s6-echo " [sigterm-dbus-daemon] PID:${PID}" }
      importas PID PID

      # kill process
      foreground {
          kill -TERM ${PID}
          rm ${ADDRESS_FILE}
          rm ${PID_FILE}
      }
    }
    echo [sigterm-dbus-daemon] graceful shutdown complete
  }
}
foreground {
  backtick -n ADDRESS_FILE { redirfd -w 2 /dev/null s6-applyuidgid -u 1000 -g 1000 mktemp /tmp/pydbustest_address.XXXXXXXXX }
  importas ADDRESS_FILE ADDRESS_FILE

  backtick -n PID_FILE { redirfd -w 2 /dev/null s6-applyuidgid -u 1000 -g 1000 mktemp /tmp/pydbustest_pid_file.XXXXXXXXX }
  importas PID_FILE PID_FILE

  foreground { sudo chown pi:pi -R ${ADDRESS_FILE} ${PID_FILE} }
  foreground { s6-echo " [run] ADDRESS_FILE:${ADDRESS_FILE}" }
  foreground { s6-echo " [run] PID_FILE:${PID_FILE}" }
}
foreground {
  multisubstitute {
    importas ADDRESS_FILE ADDRESS_FILE
    importas PID_FILE PID_FILE
  }
}
foreground { s6-echo " [verify] ADDRESS_FILE:${ADDRESS_FILE}" }
foreground { s6-echo " [verify] PID_FILE:${PID_FILE}" }
redirfd -w 0 $ADDRESS_FILE
redirfd -w 1 $PID_FILE
s6-applyuidgid -u 1000 -g 1000 dbus-daemon --session --print-address=0 --print-pid=1 --fork

init_dbus.sh

#!/bin/bash

# original script

set -e

# Startup dbus session
ADDRESS_FILE=$(mktemp /tmp/pydbustest.XXXXXXXXX)
PID_FILE=$(mktemp /tmp/pydbustest.XXXXXXXXX)

dbus-daemon --session --print-address=0 --print-pid=1 --fork 0>"$ADDRESS_FILE" 1>"$PID_FILE"

export DBUS_SESSION_BUS_ADDRESS=$(cat "$ADDRESS_FILE")
PID=$(cat "$PID_FILE")

echo "export DBUS_SESSION_BUS_ADDRESS=$(cat "$ADDRESS_FILE")" > ~pi/.exports

echo "D-Bus per-session daemon address is: $DBUS_SESSION_BUS_ADDRESS"

trap 'kill -TERM $PID' EXIT

rm "$ADDRESS_FILE" "$PID_FILE"

This was the fix! Parallel multi-substitution is needed ... serial substitution causes problems.

#!/usr/bin/execlineb -P
# -*- mode: bash -*-
# vi: set ft=bash:

with-contenv

trap -x
{
  term
  {
    foreground
    {

      # find location of PID_FILE
      backtick -n PID_FILE { redirfd -w 2 /dev/null find /tmp -name 'pydbustest_pid_file*' -print }
      backtick -n ADDRESS_FILE { redirfd -w 2 /dev/null find /tmp -name 'pydbustest_address*' -print }
      backtick -n PID { redirfd -w 2 /dev/null cat ${PID_FILE} }

      multisubstitute {
        importas PID_FILE PID_FILE
        importas ADDRESS_FILE ADDRESS_FILE
        importas PID PID
      }

      foreground { s6-echo " [sigterm-dbus-daemon] PID_FILE:${PID_FILE}" }
      foreground { s6-echo " [sigterm-dbus-daemon] ADDRESS_FILE:${ADDRESS_FILE}" }
      foreground { s6-echo " [sigterm-dbus-daemon] PID:${PID}" }

      # kill process
      foreground {
          kill -TERM ${PID}
          rm ${ADDRESS_FILE}
          rm ${PID_FILE}
      }
    }
    s6-echo " [sigterm-dbus-daemon] graceful shutdown complete"
  }
}

backtick -n ADDRESS_FILE { redirfd -w 2 /dev/null s6-applyuidgid -u 1000 -g 1000 mktemp /tmp/pydbustest_address.XXXXXXXXX }
backtick -n PID_FILE { redirfd -w 2 /dev/null s6-applyuidgid -u 1000 -g 1000 mktemp /tmp/pydbustest_pid_file.XXXXXXXXX }

multisubstitute {
  importas ADDRESS_FILE ADDRESS_FILE
  importas PID_FILE PID_FILE
  # NOTE: This is needed for pydbus
  importas DBUS_SESSION_BUS_ADDRESS DBUS_SESSION_BUS_ADDRESS
}

foreground { sudo chown pi:pi -R ${ADDRESS_FILE} ${PID_FILE} }
foreground { s6-echo " [run] ADDRESS_FILE:${ADDRESS_FILE}" }
foreground { s6-echo " [run] PID_FILE:${PID_FILE}" }

foreground { s6-echo " [run] starting dbus-daemon ..." }

# https://github.com/search?q=redirfd+-w+1&type=Code&utf8=%E2%9C%93
# https://github.com/shirley-zhou/CS111/blob/052f16e0efcf5c83d042b7ef43f0b0f0f9bbb9df/lab1/exec5.sh
# NOTE: redirfd program
# redirfd redirects a given file descriptor to a file, then executes a program.
# redirfd [ -r | -w | -u | -a | -c | -x ] [ -n | -b ] fd file prog...
# -w : open file for writing, truncating it if it already exists.
# 0	Standard input	STDIN_FILENO	stdin
# 1	Standard output	STDOUT_FILENO	stdout
# 2	Standard error	STDERR_FILENO	stderr
redirfd -w 0 $ADDRESS_FILE
redirfd -w 1 $PID_FILE
s6-applyuidgid -u 1000 -g 1000 dbus-daemon --session --print-address=0 --print-pid=1 --fork