micro-utils/coreutils/sleep.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

double convert(const char *num) {
	if (atof(num) <= 0) {
		fprintf(stderr, "sleep: %s < 1\n", num);
		exit(1);
	}

	return atof(num);
}

int main(const int argc, const char **argv) {
	if (argc == 1 || !strcmp(argv[argc - 1], "-h")) {
		printf("sleep [num[m - minute / h - hour / d - days]] / [inf (infinity)]\n");
		return 0;
	}

	if (!strcmp(argv[1], "inf"))
		for (;;)
			sleep(1);

	double sec = 0;
	for (int i = 1; i < argc; i++) {
		switch (argv[i][strlen(argv[i]) - 1]) {
			case 'd':
				sec += convert(argv[i]) * 86400;
				break;

			case 'h':
				sec += convert(argv[i]) * 3600;
				break;

			case 'm':
				sec += convert(argv[i]) * 60;
				break;

			default:
				sec += convert(argv[i]);
		}
	}

	usleep(sec * 1000000);
	return 0;
}