#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <string.h>

const char *_progname;

static int send_break(const char *port)
{
    int err;
    int fd = open(port, O_RDWR|O_NOCTTY|O_NONBLOCK);

    if (fd < 0)
	goto fail;

    tcdrain(fd);

    do {
	err = tcsendbreak(fd, 0);
    } while (err && errno == EAGAIN);

    if (err)
	goto fail;

    close(fd);
    return 0;

fail:
    fprintf(stderr, "%s: %s: %s\n", _progname, port, strerror(errno));
    if (fd >= 0)
	close(fd);
    return -1;
}

int main(int argc, char *argv[])
{
    _progname = argv[0];
    
    if (argc != 2) {
	fprintf(stderr, "Usage: %s port\n", _progname);
	exit(1);
    }

    send_break(argv[1]);
    return 0;
}