feature: kmalloc kfree and krealloc are good

src/shell/exec.c

@@ -115,7 +115,8 @@ void shell_init(void)
 			}
 		}
 		if (invalid && screen->line[0])
-			kprintf("invalid command: %s\n", screen->line);
+			kprintf(KERN_WARNING "invalid command: %s\n",
+			        screen->line);
 		memset(screen->line, '\0', sizeof(screen->line));
 	}
 }