DualScope: Run two steam instances with gamescope with different user accounts (split screen on any game!)

dualscope.sh

#!/bin/bash

# a little script i made to open two gamescope sessions of steam
# i SUCK at making bash script, so expect a lot of bugs or issues :<
# made for arch linux in mind
# you need another account on your device to use this

# if u use pipewire and your audio is not working, take a look at this:
# https://wiki.archlinux.org/title/PipeWire#Multi-user_audio_sharing

# The gamescope params for both of the processes
GAMESCOPE_PARAMS="-e -b -w 960 -h 360 -W 1440 -H 540"
# Params for both steams
STEAM_PARAMS="-gamepadui"

# The secondary account you will use
RUNAS_ACC="YOUR SECONDARY ACCOUNT"

GAMESCOPE_BIN="/usr/bin/gamescope"
RUNAS_BIN="/usr/bin/run-as"
STEAM_BIN="/usr/bin/steam"

CHANGED_DEVICES=()
GAMESCOPE_PRIMARY_PID=""
GAMESCOPE_SECONDARYPID=""

# hiding kde panels using this:
# https://github.com/luisbocanegra/plasma-panel-colorizer
toggle_panels() {
  local state="$1"
  local value="false"
  if [ "$state" = "true" ]; then
    value="true"
  fi

  local status="string:stockPanelSettings.visible {\"enabled\": true, \"value\": $value}"
  dbus-send --session --type=signal /preset "luisbocanegra.panel.colorizer.all.property" "$status"
}

startup() {
  echo "Hiding the KDE panels!"
  toggle_panels "false"
}

cleanup() {
  echo "Showing the KDE panels again"
  toggle_panels "true"
  echo "Returning ownership to every device"
  return_devices_ownership

  if [[ -n "$GAMESCOPE_PRIMARY_PID" ]]; then
    echo "Killing primary gamescope..."
    kill -TERM "$GAMESCOPE_PRIMARY_PID" 2>/dev/null || true
  fi

  if [[ -n "$GAMESCOPE_SECONDARY_PID" ]]; then
    echo "Killing secondary gamescope..."
    kill -TERM "$GAMESCOPE_SECONDARY_PID" 2>/dev/null || true
  fi
}

show_devices_list() {
  local devices=""
  local name=""
  while IFS= read -r line; do
    if [[ $line == N:\ Name=* ]]; then
      name=$(echo "$line" | sed 's/N: Name=//' | tr -d '"')
    fi
    if [[ $line == *Handlers=* ]]; then
      local event_dev=$(echo "$line" | grep -o 'event[0-9]*' | sed 's/event//')

      if [[ -n $name && -n $event_dev ]]; then
        # aditional info 4 controllers
        local device_info=""
        if [[ $name == *"Xbox"* || $name == *"Controller"* || $name == *"Gamepad"* || $name == *"Joystick"* ]]; then
          device_info=" 󰊗"
        elif [[ $name == *"Keyboard"* || $name == *"keyboard"* ]]; then
          device_info=" ⌨️"
        elif [[ $name == *"Mouse"* || $name == *"mouse"* ]]; then
          device_info=" 󰍽"
        fi

        devices+="$event_dev - $name$device_info"$'\n'
        name=""
      fi
    fi
  done < /proc/bus/input/devices

  echo -e "$devices"
}

change_device_ownership() {
  local profile="$1"
  local device="$2"
  local device_path="/dev/input/event$device"

  sudo chown "$profile" "$device_path"
  sudo chmod 600 "$device_path"
}

get_devices_to_change() {
  local profile="$1"
  echo "Select the devices to transfer for the $profile profile:"
  show_devices_list

  echo "Please, input your device list divided by a comma (1,2,3,4,etc):"
  read input_string

  IFS=',' read -r -a NEW_DEVICES <<< "$input_string"
  CHANGED_DEVICES+=("${NEW_DEVICES[@]}")

  for device in "${NEW_DEVICES[@]}"; do
    change_device_ownership "$profile" "$device"
  done
}

return_devices_ownership() {
  for device in "${CHANGED_DEVICES[@]}"; do
    local device_path="/dev/input/event$device"
    sudo chown root:input "$device_path" "$device_path"
    sudo chmod 660 "$device_path" "$device_path"
  done
}

primary_gamescope() {
  eval "$GAMESCOPE_BIN $GAMESCOPE_PARAMS -- $STEAM_BIN $STEAM_PARAMS"
  GAMESCOPE_PRIMARY_PID=$!
}

secondary_gamescope() {
  eval "sudo $RUNAS_BIN -X $RUNAS_ACC -- env PULSE_SERVER=tcp:127.0.0.1:4713 $GAMESCOPE_BIN $GAMESCOPE_PARAMS -- $STEAM_BIN $STEAM_PARAMS"
  GAMESCOPE_SECONDARY_PID=$!
}

trap cleanup EXIT INT TERM

main() {
  echo "DualScope by NaviVani "

  if [[ $EUID -eq 0 ]]; then
    echo "Running as sudo, exiting..."
    exit 1
  fi

  for bin in "$GAMESCOPE_BIN" "$STEAM_BIN" "$RUNAS_BIN"; do
    if [[ ! -x "$bin" ]]; then
      echo "The $bin executable was not found, exiting..."
      exit 1
    fi
  done

  get_devices_to_change "$(whoami)"
  get_devices_to_change "$RUNAS_ACC"

  echo "Killing steam before starting..."
  pkill steam

  while pgrep steam > /dev/null; do
    sleep 1
  done

  startup

  echo "Opening gamescope sessions!"
  secondary_gamescope &
  primary_gamescope
}

main "$@"

Hey! discovered your script and thought. Yes! that's an idea! so I took a few minutes and made it compatible with arch. I thought since it was your original idea ill give you my script based on yours. Free use for anyone. oh and fyi, managing input through system paths is stupid difficult with little pay off. It's easier to use steams controller isolation and simply disable input from that specific controller.

#!/usr/bin/env bash

DualScope (single-user, Garuda/Arch, two Steam instances)

Launch two Gamescope + Steam sessions with isolated runtimes.

set -euo pipefail

PRIMARY_W=1280
PRIMARY_H=720
SECONDARY_W=1280
SECONDARY_H=720

PRIMARY_RATE="60"
SECONDARY_RATE="60"

STEAM_PARAMS="-gamepadui"

GAMESCOPE_BIN="/usr/bin/gamescope"
STEAM_BIN="/usr/bin/steam"

COMMON_GAMESCOPE_FLAGS=(-e -b)

PRIMARY_PID=""
SECONDARY_PID=""

log() { printf "[DualScope] %s\n" "$*"; }

require_bin() {
local bin="$1"
if [[ ! -x "$bin" ]]; then
log "Missing binary: $bin"
exit 1
fi
}

cleanup() {
[[ -n "${PRIMARY_PID}" ]] && kill -TERM "${PRIMARY_PID}" 2>/dev/null || true
[[ -n "${SECONDARY_PID}" ]] && kill -TERM "${SECONDARY_PID}" 2>/dev/null || true
}
trap cleanup EXIT INT TERM

build_gs_args() {
local w="$1" h="$2" rate="${3:-}"
local args=("${COMMON_GAMESCOPE_FLAGS[@]}" -w "${w}" -h "${h}" -W "${w}" -H "${h}")
[[ -n "${rate}" ]] && args+=(-r "${rate}")
echo "${args[@]}"
}

launch_primary() {
local args
args=$(build_gs_args "${PRIMARY_W}" "${PRIMARY_H}" "${PRIMARY_RATE}")
log "Launching primary Steam..."
"${GAMESCOPE_BIN}" ${args} -- "${STEAM_BIN}" ${STEAM_PARAMS} &
PRIMARY_PID=$!
}

launch_secondary() {
local args
args=$(build_gs_args "${SECONDARY_W}" "${SECONDARY_H}" "${SECONDARY_RATE}")
log "Launching secondary Steam with isolated runtime..."

Create a separate runtime dir for the second instance

mkdir -p "$HOME/.steam-second"
HOME="$HOME/.steam-second" "${GAMESCOPE_BIN}" ${args} -- "${STEAM_BIN}" ${STEAM_PARAMS} &
SECONDARY_PID=$!
}

main() {
if [[ $EUID -eq 0 ]]; then
log "Do not run as root."
exit 1
fi

require_bin "${GAMESCOPE_BIN}"
require_bin "${STEAM_BIN}"

log "Launching two independent Steam+Gamescope sessions..."
launch_primary
sleep 1
launch_secondary

log "Primary PID: ${PRIMARY_PID}"
log "Secondary PID: ${SECONDARY_PID}"

wait "${PRIMARY_PID}" || true
wait "${SECONDARY_PID}" || true
}

main "$@"