[ALTERNATIVE] TinyALSA version

[MarcoRavich]

It could be interesting - even more for @bfields' original script applications - to have a slimmer/lighter/better-latency version for lower specs devices, so here's a TinyALSA (which don't support probing unfortunately):

#!/bin/sh
#
# tinyALSA-compatible recorder script
# Original: FORART/hALSAmrec, arecord version
# Adapted for tinycap (tinyALSA)
#
# This program is free software: see <https://www.gnu.org/licenses/>.
#

# CONFIGURE THESE FOR YOUR HARDWARE
CHANNELS=2
RATE=48000
FORMAT=S16_LE   # One of: S8, S16_LE, S24_LE, S32_LE, etc.

MNT=/tmp/mnt
recorder=""

trap 'true' SIGHUP

sleep infinity &
dummy=$!

trap '	kill $dummy;
	[ -n "$recorder" ] && kill $recorder;
	umount -l "$MNT";
	exit'	SIGTERM

first=0

while true; do
	if [ $first -eq 0 ]; then first=1; else
		if [ -n "$recorder" ]; then waiton=$recorder;
					else waiton=$dummy; fi
		wait $waiton
	fi

	# Detect the only exFAT partition available in the system
	disk=""
	exfat_parts=$(lsblk -o NAME,FSTYPE -nr | awk '$2=="exfat"{print "/dev/"$1}')
	count=$(echo "$exfat_parts" | wc -w)
	if [ "$count" -eq 1 ]; then
		disk="$exfat_parts"
	fi

	[ -e "$disk" ] && [ -c /dev/snd/pcmC0D0c ] # crude "soundcard present" test
	ready=$?
	if [ -n "$recorder" ] && [ ! -e /proc/$recorder ]; then
		recorder=""
		umount -l "$MNT"
	fi
	if [ $ready -ne 0 ]; then
		if [ -n "$recorder" ]; then
			umount -l "$MNT"
			kill -9 $recorder
			recorder=""
		fi
		continue
	fi
	if [ -n "$recorder" ]; then continue; fi

	mkdir -p "$MNT"
	mount $disk "$MNT" || continue

	# Check available disk space (after mounting, before recording)
	avail_kb=$(df -k "$MNT" | awk 'NR==2 {print $4}')
	avail_mb=$((avail_kb / 1024))
	if [ "$avail_mb" -le 100 ]; then
		if [ -n "$recorder" ]; then
			kill -9 $recorder
			recorder=""
		fi
		umount -l "$MNT"
		sleep 5
		continue
	fi

	while true; do
		name=$(date +%s)
		logfile="${MNT}/${name}.log"
		if [ ! -e "$logfile" ]; then break; fi
		sleep 1
	done

	# Start recording with tinycap
	filename="${name}_${CHANNELS}-${RATE}-${FORMAT}"
	tinycap "${MNT}/${filename}.wav" -c $CHANNELS -r $RATE -b 16 &
	recorder=$!
done