Use ALSA to perform loopback record

loopback-record.sh

#!/usr/bin/env bash

DATE_HASH=$(date '+%Y%m%d%H%M%S')
DEFAULT_LOCATION="$HOME/recording-$DATE_HASH.wav"

printf "\e[1mCreating loopback devices...\e[0m\n\n"

sudo modprobe snd-aloop

RAW_LOOPBACK_DEVICES=$(aplay -l | grep Loopback | sed -E "s/card\s([0-9]+).*device\s([0-9]*).*/hw:\1,\2/g" -)
LOOPBACK_DEVICES=($RAW_LOOPBACK_DEVICES)

printf "\e[1mFound loopback devices\e[0m\n"

printf '* %s\n' "${LOOPBACK_DEVICES[@]}"

USED_DEVICE=${LOOPBACK_DEVICES[${#LOOPBACK_DEVICES[@]}-1]}

printf "\n\e[1mSelect \e[7m$USED_DEVICE\e[27m as default ALSA device\n"
read -p "Press Enter to continue..."

printf "\n\e[1mRecording using \e[7m$USED_DEVICE\e[27m on \e[7m$DEFAULT_LOCATION\e[27m \n(Use Ctrl+C to stop)\e[0m\n"

arecord -D $USED_DEVICE -f cd -vv $DEFAULT_LOCATION