The interpreter recognizes several switches described below, which may appear anywhere in the command line and apply to all files thereafter. This message also lists the available devices. Ghostscript may be built with multiple output devices. Ghostscript normally opens the first one and directs output to it. Note that this switch must precede the first .ps file, and only its first invocation has any effect.
All output then goes to the printer instead of the display until further notice.
If you select a printer as the output device, Ghostscript also allows you to control where the device sends its output. Normally, output goes directly to a scratch file on Unix systems. Each file will receive one page of output. On Unix systems, you can send the output directly to a pipe. When Ghostscript finishes executing the file, it exits back to the shell.