A Brief Guide to PostScript

What Are PostScript Files?

PostScript files are plain text files that contain PostScript code. PostScript is a page description language developed by the Adobe corporation for specifying how a printer should render a page of text or graphics. It is a stack-based, postfix programming language (which means that its syntax resembles that of a "reverse Polish notation" calculator) that performs calculations and draws images; PostScript files are not simply bitmapped representations of graphics (although they can contain bitmaps). By describing how the image is drawn, rather than providing a pixelized representation of it, PostScript files can be printed on a variety of printers or viewed on a variety of machines, always optimally using the resolution available.

PostScript files usually have names that end with the suffix ".ps", although Encapsulated PostScript files (which can contain the description of a graphic no more than one page in size) usually end with a ".eps" suffix.

How Do I View or Print a PostScript File?

You need a PostScript printer to print PostScript files, or you have to be running a version of GhostScript, a PostScript interpreter that can usually plot a PostScript file on your screen, and sometimes print it on a non-PostScript printer (sorry to be so vague about this, but users on various platforms report mixed results with this program). You can find versions of GhostScript for various platforms in the machine-specific software archives mentioned in the Acoustic Guitar Resources page that hosts this page, or at the GhostScript, GhostView and GSview Home Page. Some web browsers are configured to run GhostScript automatically when you access a link to a PostScript file. This is particularly true for Unix platforms, since GhostScript runs very well on these platforms. GhostView is a particularly full-featured version of GhostScript and is available on various platforms. On Unix platforms it is usually accessed with the gv command.

If you do have a PostScript printer (typically a laser printer), life is easiest if you also happen to be on a Unix platform. In that case you can usually submit a PostScript file to the printer with the lpr command (run the Unix manual command, man lpr, to learn how to use lpr on your system).

On a Mac or PC with a PostScript printer, you might have to suitably change the type of the PostScript file, read it into a PostScript-capable application (such as Adobe Illustrator or Adobe Pagemaker), or run a separate PostScript printing utility. Several such utilities are available for free from the various machine-specific software archives. A nice web interface to many archives of software for all major platforms is The Virtual Software Library.

Mac users will find more detailed information on printing PostScript files in the Macintosh Miscellaneous Frequently Asked Questions document regularly posted to the comp.sys.mac newsgroup hierarchy. PC users will find information for their platform at????

If you don't have a PostScript printer (most inkjet printers are not PostScript printers), you might be able to print a PostScript file using GhostView. But the best solution is probably to convert the PostScript file to a PDF file, and then use a PDF viewer/printer like Acrobat Reader to print it. The GhostScript package includes PostScript-to-PDF conversion software that works reliably on most platforms.

As a final option for printing a PostScript file, you might consider saving it to a floppy disk and taking it to a friend with a PostScript printer. Lacking such a friend, you might consider taking the file to Kinkos or some other similar copying/printing firm that has computers for doing Desk Top Publishing. They are likely to have someone who can print the file for you for a nominal fee.

How Do I Write or Modify PostScript Files?

Since PostScript is a text-based programming language, you can edit PostScript files with any text editor or word processor. However, some PostScript files contain binary information (stored in hexadecimal format) specifying a font or a bitmapped image. This information may appear on a single very long line, which may cause problems for some text editors.

Some self-documented code (such as the blank music paper files included in the Acoustic Guitar Resources page) includes enough information for complete PostScript novices to perform simple modifications such as adjusting page size or line widths and spacings. For more sophisticated modifications, or to write your own code from scratch, you need to know at least some of the PostScript language. The definitive references are the various books published by Adobe, often available in good bookstores and computer stores. But there are some free resources on the web for learning basic PostScript. Three particularly useful documents for beginner PostScript programmers are:

P. J. Weingartner's A First Guide to PostScript;
The PostScript Level 2 Quick Reference Guide, as posted to comp.sources.postscript (page 1 and page 2); and
The FAQ document of the comp.lang.postscript USENET newsgroup, available in both text and PostScript formats (this is a long document).

You'll find other links to useful on-line PostScript resources at these locations:

Good luck!

loredo@spacenet.tn.cornell.edu