execute function from hw4.c

hw4_execute.c

static void execute(int argc, char *argv[])
{
    pid_t childpid; /* child process ID */

    childpid = fork();
    if (childpid == -1) { /* in parent (returned error) */
        perror("fork"); /* perror => print error string of last system call */
        printf("  (failed to execute command)\n");
    }
    if (childpid == 0) { /* child:  in child, childpid was set to 0 */
        /* Executes command in argv[0];  It searches for that file in
	 *  the directories specified by the environment variable PATH.
         */
        if (-1 == execvp(argv[0], argv)) {
          perror("execvp");
          printf("  (couldn't find command)\n");
        }
	/* NOT REACHED unless error occurred */
        exit(1);
    } else /* parent:  in parent, childpid was set to pid of child process */
        waitpid(childpid, NULL, 0);  /* wait until child process finishes */
    return;
}