#include <stdio.h>
#include <stdlib.h>
#include <string.h>
unsigned int nullline;

int printvars(const int len, const char **names) {
	int ret = 0;

	for (int i = 0; i < len; i++) {
		char *val = getenv(names[i]);
		if (!val) {
			ret = 1;
			continue;
		}

		printf("%s%c", val, (nullline == 1) ? 0 : '\n');
	}

	return ret;
}

int main(const int argc, const char **argv, const char **envp) {
	int i;
	for (i = 1; i < argc; i++) {
		if (argv[i][0] != '-')
			break;

		else if (!strcmp(argv[i], "-0"))
			nullline = 1;

		else if (!strcmp(argv[i], "--help")) {
			printf("printenv [-n (end each output line with NUL, not newline)]\n");
			return 0;
		}
	}

	if (i == argc)
		while (*envp)
			printf("%s%c", *envp++, (nullline == 1) ? 0 : '\n');

	else
		return printvars(argc - i, argv + i);

	return 0;
}