General information about PostScript previewing at RZG

Ghostscript (see the corresponding man pages) is a programming language similar to Adobe Systems' PostScript (tm) language, which is in turn similar to Forth. Gs reads files in sequence and executes them as Ghostscript programs. After doing this, it reads further input from the standard input stream (normally the keyboard). Each line is interpreted separately. To exit from the interpreter, enter the `quit' command. The interpreter also exits gracefully if it encounters end-of-file. Typing the interrupt character (e.g. Control-C) is also safe.
You can get a help message by invoking Ghostscript with the -h option. This message also lists the available devices.

The ghostview program (see the corresponding man pages) provides an X11 user interface for the ghostscript interpreter. Ghostview and ghostscript function as two cooperating programs. Ghostview creates the viewing window and ghostscript draws in it.
Don't be alarmed by the number of options. Generally, one invokes ghostview with just one parameter, the name of the file to be previewed. If the filename is ``-'', ghostview will read from ``stdin''. The options provide a way to set X resources from the command line for a single invocation of ghostview. For that reason, discussion of the options is delayed until after the X resources are discussed.
Ghostview will check to see if the file has been modified just before it displays a page or when the application is deiconified. If the file has changed, it will reopen the file.