Popular formats are PNG, PDF, and jpeg, and they can then be presented either on the fly or directly to an X terminal, Web page, or a general graphic viewer utility.
For instance, on Mac OS X, the wall utility — short for "write all," because it writes a message to every physical or virtual terminal device — is setgid tty (as shown above).
例如，在Mac OS X中，wall工具(“write all”的缩写，因其会将某个消息写入所有物理或虚拟终端设备而得名)的setgid被设为tty(如上所示)。