Play audio from line-in in Pulseaudio; unload when finished.

pulseinput.sh

#!/bin/bash
set -e

function get_loopback(){
    # Detect the module number module-loopback is on
    # If it isn't loaded, then load it.
    loopback=`pactl list short modules | grep module-loopback | awk '{print $1}'`
    if [ "$loopback" == "" ]; then
        loopback=`pactl load-module module-loopback`
    fi
    echo $loopback
}

function get_active_port(){
    # Find the active port on the source
    port=`pactl list sources | grep "Active Port:" | awk '{print $3}'`
    echo $port
}

function get_running_source(){
    # Find the source which is running
    src=`pactl list short sources | grep "RUNNING" | awk '{print $1}'`
    echo $src
}

function main_loop(){
    echo "Setting source $2 to use port $4"
    pactl set-source-port $2 $4
    echo "Press 'q' to quit playing from $4"
    while read -n 1 user; do
        if [ "$user" == "q" ]; then
            echo ""
            echo "Unloading module $1, Restoring source $2 back to port $3"
            # should detect the previously used input and store it
            pactl set-source-port $2 $3
            pactl unload-module $1
            exit
        fi
    done
}

module=$(get_loopback)
running=$(get_running_source)
prev_port=$(get_active_port)
main_loop $module $running $prev_port analog-input-linein