nudge.c in git
NUDGE(1)                FreeBSD General Commands Manual               NUDGE(1)

NAME
     nudge – terminal vibrator

SYNOPSIS
     nudge [-f file] [-n count] [-s shake] [-t delay]

DESCRIPTION
     The nudge utility nudges the terminal.  An xterm(1) compatible terminal
     is required.

     The arguments are as follows:

     -f file
             Open the terminal named by file.  The default is /dev/tty.

     -n count
             Set the number of times to nudge the terminal.  The default is 2.

     -s shake
             Set the shake intensity in pixels.  The default is 10.

     -t delay
             Set the interval between shakes in milliseconds.  The default is
             20.

FreeBSD 12.1-RELEASE-p8        September 4, 2020       FreeBSD 12.1-RELEASE-p8
/* Copyright (C) 2020  C. McEnroe <june@causal.agency>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>
#include <termios.h>
#include <unistd.h>

static int shake = 10;
static int delay = 20000;
static int count = 2;

static void move(int tty, int x, int y) {
	dprintf(tty, "\33[3;%d;%dt", x, y);
	usleep(delay);
}

int main(int argc, char *argv[]) {
	const char *path = "/dev/tty";
	for (int opt; 0 < (opt = getopt(argc, argv, "f:n:s:t:"));) {
		switch (opt) {
			break; case 'f': path = optarg;
			break; case 'n': count = atoi(optarg);
			break; case 's': shake = atoi(optarg);
			break; case 't': delay = atoi(optarg) * 1000;
			break; default:  return EX_USAGE;
		}
	}

	int tty = open(path, O_RDWR);
	if (tty < 0) err(EX_OSFILE, "%s", path);

	struct termios save;
	int error = tcgetattr(tty, &save);
	if (error) err(EX_IOERR, "tcgetattr");

	struct termios raw = save;
	cfmakeraw(&raw);
	error = tcsetattr(tty, TCSAFLUSH, &raw);
	if (error) err(EX_IOERR, "tcsetattr");

	char buf[256];
	dprintf(tty, "\33[13t");
	ssize_t len = read(tty, buf, sizeof(buf) - 1);
	buf[(len < 0 ? 0 : len)] = '\0';

	int x, y;
	int n = sscanf(buf, "\33[3;%d;%dt", &x, &y);

	error = tcsetattr(tty, TCSANOW, &save);
	if (error) err(EX_IOERR, "tcsetattr");
	if (n < 2) return EX_CONFIG;

	dprintf(tty, "\33[5t");
	for (int i = 0; i < count; ++i) {
		move(tty, x - shake, y);
		move(tty, x, y + shake);
		move(tty, x + shake, y);
		move(tty, x, y - shake);
		move(tty, x, y);
	}
}