A short code example to show how to overwrite the contents of argv. It is useful for when a password is passed on the command line and it should not be visible in the process list to other users on the same machine.

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

int main(int argc, char **argv) {
        int i = 0;
        int len = 0;

        if (argc < 2) {
                printf("Usage: %s <some argument>\n", argv[0]);
                exit(EXIT_FAILURE);
        }

        len = strlen(argv[1]);
        for(i=0;i<len;i++) {
                argv[1][i] = 'x';
        }

        system("ps f");

        return 0;
}