#define _POSIX_C_SOURCE 200809L
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

/* Public domain by Nathan Wagner */

extern char **environ;

static void printenv() {
	char **env;
	for (env = environ; *env; env++) {
		printf("%s\n", *env);
	}
}

static void clearenv() {
	char var[1024]; /* TODO how long can the name be ? */
	char *s;
	int i;

	while (*environ) {
		i = 0;
		s = *environ;
		while (*s && *s != '=') {
			var[i++] = *s++;
		}
		var[i] = 0;
		unsetenv(var);
	}
}

int main(int ac, char *av[]) {
	int arg;
	arg = 1;
	if (arg < ac && !strcmp(av[arg], "-i")) {
		clearenv();
		arg++;
	}
	while (arg < ac) {
		char *eq;
		eq = strchr(av[arg], '=');
		if (eq) {
			*eq = 0;
			setenv(av[arg], eq+1, 1);
			*eq = '=';
		} else {
			break;
		}
		arg++;
	}

	if (arg >= ac) {
		printenv();
		return 0;
	}

	execvp(av[arg], &av[arg]);
	return 0;
}