Because these functions are provided using VxFS-specific IOCTL system calls, most existing UNIX system applications do not use them. The cp, cpio, and mv utilities use the functions to preserve extent attributes and allocate space more efficiently. The current attributes of a file can be listed using the getext or ls command. The functions can also improve performance for custom applications. For portability reasons, these applications must check which file system type they are using before using these functions.