# include<stdio.h>     #include<stdlib.h>   #include<unistd.h>    #include<fcntl.h>    #include<sys/types.h>  #include<sys/stat.h>                                                    #include<string.h>    int main()        {             pid_t id=fork();   if(id==0)         {           printf("child is running/n");   sleep(1);      char* env[]={"MYENV=/A/B/C/D/AAAA",NULL};  char* argv[]={"ls","-l","-n","-i",NULL}; // execl("/bin/ls","ls","-l","-n","-i",NULL);  // execlp("ls","ls","-l","-n","-i",NULL); //  execv("/bin/ls",argv);   // execvp("ls",argv);                            // execle("./myenv","myenv",NULL,env);      execve("./myenv",argv,env);          printf("child id done/n");  //exec成功的話不執行此語句      exit(1);       }                   else                                                            {                pid_t ret=waitpid(id, NULL,0);      if(ret>0)         {              printf("father wait success/n"); }         else{            printf("child quit not normal/n");                   }   }   return 0;                                              }