When Postscript graphics are included in a document, xdvi is powerless to render them, because it knows nothing at all about Postscript. xdvi operates on the user's DVI file and font files to generate a screen image, and at the point where the graphic is included, the DVI file simply has a note to the dvips post-processor about where to find the graphics. When xdvi encounters such a note, it simply leaves a blank box where a diagram will appear in the final printed version. Most of the time, this is fine, but there are circumstances where whatever is missing has a close enough relationship to the document that to view the document without it is insufficient for proof-reading purposes, and the user really needs a method of proof-reading the actual Postscript shortly to be sent to a printer.
Ghostscript is a public-domain software package that interprets Postscript page descriptions in an X window. It is adequate but suffers from a highly unsophisticated user interface rather akin to entering text direct from keyboard to laser printer. Thankfully for the majority of the user community, Ghostview is an X wrapper for Ghostscript which transforms the basic Ghostscript user interface into a full-scale X application, complete with menus, buttons, scrollbars and the like. The general previewing user is strongly recommended to stick to Ghostview.
Ghostview, as might be expected, operates on the Postscript version of the document, the .ps file. Probably the most common mistake made in the use of and previewers is forgetting to regenerate the file to be previewed and becoming increasingly annoyed at the computer's failure to take any notice of the last two hours' edit session. Remember, the Ghostview stage, if used, happens between dvips and lp!
To start up Ghostview, simply enter
ghostview file.pswhere `file.ps' is the (full) name of the Postscript file you wish to preview. Ghostview is one of those programs whose behaviour is only really learnable by experiment, and there is little to be gained from listing the five most important options here. The manual page itself states
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...The options provide a way to set X resources from the command line for a single invocation of ghostview.It should be stated here that given that Ghostscript is not necessarily a complete, semantically-equivalent-to-a-laserprinter implementation of a Postscript interpreter. Indeed, the documentation that accompanies the software explicitly states that it is not, for copyright/licensing reasons. Users should remember that it is only close to Postscript, and should expect to see occasional `blips' in its rendering of Postscript objects (not to mention the occasional straightforward core dump!).