> /"$mypath"/Untitled.m4a
chmod 666 /"$mypath"/Untitled.m4a

#!/bin/sh
# Usage:- [./]AUDIO_CAPTURE.sh <number_of_seconds_from_1_upwards>
#
# This DEMO shell script uses a virgin OSX Sierra install only, nothing else is required.
# The conversion for this DEMO is mono, 8 bit, unsigned integer at 48000 sps but it is
# easy to convert to just about anything, 'man afconvert'...
#
# This creates a sample which is then saved to '/"$mypath"/Untitled.m4a' which is then converted
# to '/"$mypath"/Untitled.wav' file. Both formats are then played using 'afplay'.
#
# From the current directory, './AUDIO_CAPTURE.sh 5' gives about 5 seconds of recording.
#
# Use the internal built in microphone as a test.

# Time for the recording.
seconds="$1"
# Some very basic error checking.
if [ "$seconds" = "" ] || [ "$seconds" -le "1" ]
then
	seconds=1
fi

# 'mypath' should be in Applescript format, NOT POSIX format.
# E.G. 'Users:myhome:Desktop'. There is no need for leading and trailing colons - see below.
# This could be a command line second argument but is not given '$2' here.
mypath='tmp'

SAMPLE()
{
> /"$mypath"/Untitled.m4a
chmod 666 /"$mypath"/Untitled.m4a
osascript << AppleSampler
tell application "QuickTime Player"
	activate
	set savePath to "Macintosh HD:" & "$mypath" & ":Untitled.m4a"
	set recording to new audio recording
	set visible of front window to false
	delay 3
	start recording
	delay "$1"
	stop recording
	export document "Untitled" in file savePath using settings preset "Audio Only"
	close (every document whose name contains "Untitled") saving no
	tell application "System Events" to click menu item "Hide Export Progress" of menu "Window" of menu bar 1 of process "QuickTime Player"
	-- quit
end tell
AppleSampler
# 'wait' added for fullness only.
wait
}

# Use the function to create a _background_ recording.
SAMPLE "$seconds"

# Example of conversion to a WAVE file.
afconvert -f 'WAVE' -c 1 -d UI8@48000 /"$mypath"/Untitled.m4a /"$mypath"/Untitled.wav
ls -l /"$mypath"/Untitled.*

# Playback both files.
afplay /"$mypath"/Untitled.m4a
sleep 1
afplay /"$mypath"/Untitled.wav
exit 0