#include <stdlib.h> //getenv, atoi
#include <stdio.h> //printf

int main(){
	// pointer to a char
	char *repstext=getenv("reps");
	int reps = repstext ? atoi(repstext) : 10;
	
	char *msg = getenv("msg");
	if (!msg) msg = "Hello.";
	
	for (int i=0; i< reps; i++)
		printf("%s\n", msg);
}