Get Environment Variable Mem Address

getenvaddr.c

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

# USAGE:
# ~$ export PWN='echo 1'
# ~$ ./getenvaddr PWN ./pwnme
# PWN will be at 0xbfffff7d

int main(int argc, char *argv[]) {
	char *ptr;

	if(argc < 3) {
		printf("Usage: %s <environment variable> <target program name>\n", argv[0]);
		exit(0);
	}
	ptr = getenv(argv[1]); /* get env var location */
	ptr += (strlen(argv[0]) - strlen(argv[2]))*2; /* adjust for program name */
	printf("%s will be at %p\n", argv[1], ptr);
}