159         printf("ERROR: Path too long!\n");  in shell_cmd_cd()
201             printf("ERROR: Path too long!\n");  in shell_cmd_cd()
225             printf("ERROR: Cannot switch to directory: %s\n", new_path);  in shell_cmd_cd()
273     printf("\n");  in shell_cmd_ls()
292         printf("%s\n", shell_current_path);  in shell_cmd_pwd()
314         printf("ERROR: Cannot open file: %s, fd=%d\n", file_path, fd);  in shell_cmd_cat()
330             printf("ERROR: Cannot read file: %s\n", file_path);  in shell_cmd_cat()
336         printf("%s", buf);  in shell_cmd_cat()
436         printf("Failed to remove %s, retval=%d\n", full_path, retval);  in shell_cmd_rmdir()
470         printf("Failed to remove %s, retval=%d\n", full_path, retval);  in shell_cmd_rm()
511             printf("[1] %d\n", pid); // 输出子进程的pid  in shell_cmd_exec()
538         printf("Usage: Kill <pid>\n");  in shell_cmd_kill()
566         printf("Invalid argument: %s\n", argv[1]);  in shell_cmd_free()
574         printf("Failed: retval=%d", retval);  in shell_cmd_free()
578     printf("\ttotal\tused\tfree\tshared\tcache\tavailable\n");  in shell_cmd_free()
579     printf("Mem:\t");  in shell_cmd_free()
582 …printf("%ld\t%ld\t%ld\t%ld\t%ld\t%ld\t\n", mst.total >> 10, mst.used >> 10, mst.free >> 10, mst.sh…  in shell_cmd_free()
587 …printf("%ld\t%ld\t%ld\t%ld\t%ld\t%ld\t\n", mst.total >> 20, mst.used >> 20, mst.free >> 20, mst.sh…  in shell_cmd_free()