OS X (Apple)

#!/bin/sh
# FG.sh
awk '
# Clear the terminal window.
function cls()
{
	printf "\x1B[2J\x1B[H";
}

# User keyboard interrupt.
function keyboard( COMMAND )
{
	printf "Press <CR> to continue or QUIT<CR>:- ";
	getline COMMAND;
	if ( COMMAND == "QUIT" ) { exit 0 };
}
 
# Adjust the sample rate for SOX WRT its frequency.
function setrate( RATE )
{
	cls();
	FREQ=500;
	BYTES=8;
	RATE=16000;
	printf "Enter frequency required:- ";
	getline FREQ;
	RATE=(BYTES*FREQ);
	if ( RATE <= 4000 ) { RATE=4000 };
	if ( RATE >= 48000 ) { RATE=48000 };
	return RATE;
}

# Main loop...
function main()
{
	RATE=setrate();
	LOOPS=2;
	for ( LOOP = 1; LOOP <= LOOPS; ++LOOP ) { system ( "~/sox-14.4.2/sox -q -b 8 -r "RATE" -e unsigned-integer /tmp/sinewave8.raw -d trim 0 00:01 > /dev/null 2>&1" ) };
	keyboard( COMMAND );
}

# Now generate a simple sinewave and run the _main_ code.
BEGIN \
{
	system( ">" "/tmp/sinewave8.raw" );
	SINEWAVE8="Op}pN- -";
	for ( LOOP = 1; LOOP <= 16; ++LOOP ) { SINEWAVE8=SINEWAVE8 SINEWAVE8 };
	printf SINEWAVE8 > "/tmp/sinewave8.raw";
	cls();
	while( 1 ) { main() };
}'

function keyboard() {
	printf "Press <CR> to continue, or ctl-D or QUIT<CR> to exit:- ";
	if ( getline != 1 || $1 == "QUIT" ) { exit 0 }
}

	keyboard();

	keyboard( COMMAND );

function setrate( RATE )
{
	cls();
	BYTES=8;
	printf("Enter frequency required (%d <= frequency <= %d):- ",
	    int((4000 + BYTES - 1) / BYTES), ((48000 + BYTES - 1) / BYTES))
	getline FREQ;
	RATE=(BYTES*FREQ);
	if ( RATE <= 4000 ) { RATE=4000 };
	if ( RATE >= 48000 ) { RATE=48000 };
	return RATE;
}

function setrate(	FREQ, RATE )
{
	cls()
	BYTES = 8
	printf("Enter frequency to continue or ctl-D to exit.\n")
	printf("Valid frequency range: %d <= frequency <= %d:- ",
	    int((4000 + BYTES - 1) / BYTES), ((48000 + BYTES - 1) / BYTES))
	if(getline FREQ != 1 || (FREQ + 0) == 0) {
		print "Good bye."
		exit 0
	}
	RATE = (BYTES * FREQ)
	if(RATE <= 4000) RATE=4000
	if(RATE >= 48000) RATE=48000
	return RATE
}

#!/bin/sh
awk '
# Now generate a simple sinewave and run the _main_ code.
BEGIN {	# Initialize variables.
	BYTES = 8
	LOOPS = 2;
	MaxRATE = 48000
	MinRATE = 4000
	SINEWAVE8 = "Op}pN- -";
	TMPFILE = "/tmp/sinewave8.raw"

	COMMANDpt1 = "~/sox-14.4.2/sox -q -b " BYTES " -e unsigned-integer -r "
	COMMANDpt2 = " " TMPFILE " -d trim 0 00:01 > /dev/null 2>&1"

	# Create waveform file.
	for(LOOP = 1; LOOP <= 16; ++LOOP) {
		SINEWAVE8 = SINEWAVE8 SINEWAVE8
	}
	printf("%s", SINEWAVE8) > TMPFILE

	# Prompt user for first input.
	prompt()
}

# Clear the terminal window.
function cls() {
	printf "\x1B[2J\x1B[H";
}

# Prompt user for input.
function prompt() {
	# Clear the screen.
	cls()

	# Issue the prompt.
	printf("Enter frequency to continue or ctl-D to exit.\n")
	printf("Valid frequency range: %d <= frequency <= %d:- ",
	    int((MinRATE + BYTES - 1) / BYTES), ((MaxRATE + BYTES - 1) / BYTES))
}

# Process a line of user supplied input.
{	# Exit if input frequency is 0 or non-numeric.
	if($1 + 0 == 0) exit
	
	# Convert input frequency to rate.
	RATE = BYTES * $1
	if(RATE <= MinRATE) {
		RATE = MinRATE
	}
	if(RATE >= MaxRATE) {
		RATE = MaxRATE
	}

	# Print the waveform.
	for(LOOP = 1; LOOP <= LOOPS; ++LOOP) {
		system(COMMANDpt1 RATE COMMANDpt2)
	}

	# Prompt for the next input frequency.
	prompt()
}

END {	# Clear screen and print exit message.
	cls()
	print "Goodbye."

	# Remove waveform file.
	exit system("rm -rf " TMPFILE)
}'

awk 'BEGIN{printf "" >"somefile"}'