I've made this script linked to a keyboard shortcut to easily switch the audio output device used by Linux desktop manager

paswitch.sh

#!/bin/bash


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#    _____            .___.__         ________          __                 __      _________       .__  __         .__                   #
#   /  _  \  __ __  __| _/|__| ____   \_____  \  __ ___/  |_______  __ ___/  |_   /   _____/_  _  _|__|/  |_  ____ |  |__   ___________  #
#  /  /_\  \|  |  \/ __ | |  |/  _ \   /   |   \|  |  \   __\____ \|  |  \   __\  \_____  \\ \/ \/ /  \   __\/ ___\|  |  \_/ __ \_  __ \ #
# /    |    \  |  / /_/ | |  (  <_> ) /    |    \  |  /|  | |  |_> >  |  /|  |    /        \\     /|  ||  | \  \___|   Y  \  ___/|  | \/ #
# \____|__  /____/\____ | |__|\____/  \_______  /____/ |__| |   __/|____/ |__|   /_______  / \/\_/ |__||__|  \___  >___|  /\___  >__|    #
#         \/           \/                     \/            |__|                         \/                      \/     \/     \/        #
#                                                                                                                                        #
# Copyright (C) 2023 Cyril Bosselut                                                                                                      #
#                                                                                                                                        #
# paswitch is free software: you can redistribute it and/or modify                                                                       #
# it under the terms of the GNU General Public License as published by                                                                   #
# the Free Software Foundation, either version 3 of the License, or                                                                      #
# (at your option) any later version.                                                                                                    #
#                                                                                                                                        #
# paswitch is distributed in the hope that it will be useful,                                                                            #
# but WITHOUT ANY WARRANTY; without even the implied warranty of                                                                         #
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                                                                          #
# GNU General Public License for more details.                                                                                           #
#                                                                                                                                        #
# You should have received a copy of the GNU General Public License                                                                      #
# along with paswitch  If not, see <http://www.gnu.org/licenses/>.                                                                       #
#                                                                                                                                        #
##########################################################################################################################################


##
# First we check if the bridge sink exists
##
bridgeId=`pactl list short sinks | grep "bridge" | cut -f1`
if [ -z "$bridgeId" ]; then
    ##
    # Bridge does not exist so we set the volume for all sound cards
    # then we create it by loading the null-sink and the loopback modules.
    # The bridge will be the loopback input.
    # We set the bridge as the default sink so all programs will use it as output.
    ##
    echo "Setting default volume for all sound cards"
    for s in `pactl list short sinks | cut -f2`; do
        pactl set-sink-volume $s 75%
    done
    echo "Creating bridge sink"
    pactl load-module module-null-sink sink_name=bridge format=s32le channels=2 rate=96000 sink_properties="device.description='Bridge Sink'"
    pactl load-module module-loopback source="bridge.monitor"
    pactl set-default-sink bridge
    pactl set-sink-volume bridge 50%
    pactl set-sink-mute bridge 0
else
    echo "Bridge sink exists #$bridgeId"
fi

##
# We retrieve available output sinks IDs, current output ID and loopback ID
##
availableSinksString=`pactl list short sinks | grep "alsa_output" | cut -f1`
currentOutput=`pactl list short sink-inputs | grep "PipeWire" | grep "-" | cut -f2`
loopback=`pactl list short sink-inputs | grep "PipeWire" | grep "-" | cut -f1`

##
# We search the next output sink ID
##
shoudSelectNext=0
found=0
i=0
echo "Current sink: #${currentOutput}"
for sink in $availableSinksString; do
    availableSinks[$i]=$sink
    if [ $shoudSelectNext == 1 ]; then
        currentOutput=$sink
        found=1
        shoudSelectNext=0
    fi
    if [ $found == 0 ]; then
        if [ "$currentOutput" = "${sink}" ]; then
            # echo "Should select next sink"
            shoudSelectNext=1
        else
            shoudSelectNext=0
        fi
    fi
    i=$i+1
done
echo "Available sinks: ${availableSinks[@]}"
if [ $found == 0 ]; then
    ##
    # Selected sink was the last so we select the first
    ##
    currentOutput=${availableSinks[0]}
fi

##
# We set the selected sink as loopback output
##
pactl move-sink-input $loopback $currentOutput

##
# We retrieve sound card info and display a notification
##
card=`pactl list sinks | grep -A29 "Destination #$currentOutput" | grep 'alsa.card_name = ".*"$' | cut -d'"' -f2`
notify-send -a paswitch -c device -i org.kde.plasma.audiodeviceswitcher "🎧 Audio output switcher" "Audio output switched to card :\n$card" &
echo "Audio output switched to card #$currentOutput [$card]"