#include <X11/Xlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#include <string.h>

void show(char *prefix, struct tm *tm)
{
	char s[6];
	strftime(s, sizeof(s), "%H:%M", tm);
	printf("%s%s\n", prefix, s);
	fflush(stdout);
}

int main(int argc, char **argv) {
	int h, m, init = 60, opt;
	time_t t;
	struct tm *tm;
	char *prefix = "";

	while ((opt = getopt(argc, argv, "p:")) != -1) {
		switch (opt) {
		case 'p':
			prefix = optarg;
		break;
		default:
			fprintf(stderr, "Usage: %s [-p PREFIX]\n", argv[0]);
			exit(EXIT_FAILURE);
		}
	}

	while (1) {
		t = time(NULL);
		tm = localtime(&t);
		if (tm->tm_hour != h || tm->tm_min != m || init > 0) {
			show(prefix, tm);
			h = tm->tm_hour;
			m = tm->tm_min;
			init = (init > 0) ? init - 1 : 0;
		}
		sleep(1);
	}
	return 1;
}