리눅스 쉘인데요~도아주세요~

#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

#define MAX 100

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

        for(;;)
        {

                wait((char*)0);
                printf("shell-> ");

                int i=0;
                char str[MAX];
                char *ptoken;
                char *delimiter= " ";

                fgets(str, sizeof(str), stdin);

                ptoken = strtok(str, delimiter);

                while(ptoken != NULL)
                {
                        argv[i] = ptoken;
                //      printf("%s ", argv[i]);
                        i++;

                        ptoken = strtok(NULL, delimiter);
                }
                pid =fork();
                if(pid == 0){
                        execv(" 환경변수 ", argv); //"환경변수" 이부분을 getenv를 사용해서 만들어야 해요 ... 이것만 해주세요 ; _;
                        exit(1);
                }
                else{
                        wait(pid);
                }

        }

}