Script in /lib/systemd/system-sleep/ does not run

Support & Help Requests
#1

I thought scripts in this dir were run when computer resumes from a sleep state.

/lib/systemd/system-sleep/

Everything works except the cvlc command.

#!/bin/sh
if [ "${1}" == "pre" ]; then
  # Do the thing you want before suspend here, e.g.:
  echo "we are suspending at $(date)..." > /tmp/systemd_suspend_test
  cvlc --play-and-exit /usr/share/sounds/My_Sounds/Short_doorbell.wav
elif [ "${1}" == "post" ]; then
  # Do the thing you want after resume here, e.g.:
  echo "...and we are back from $(date)" >> /tmp/systemd_suspend_test
  cvlc --play-and-exit /usr/share/sounds/My_Sounds/Short_doorbell.wav
fi
#3

I understand what exec and vlc do.

But I need help understanding what "-I "dummy" "$@" is doing.

I have a script in /lib/systemd/system-sleep/ that is not working completely. It uses cvlc.

#! /bin/sh
exec /usr/bin/vlc -I "dummy" "$@"