Ghostscript

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What is Ghostscript?

Ghostscript is a PostScript and PDF interpreter, i.e., a program accepting a PostScript or PDF file as input and generating a representation of it in another format. Ghostscript was originally developed by L. Peter Deutsch of Aladdin Enterprises, California. Since September 2000, the maintainer is Raph Levien of artofcode LLC.

Ghostscript's Basic Architecture

Ghostscript is divided into a kernel, which understands PostScript and PDF, and so-called device drivers (or output modules). The latter are called from the kernel to do basic drawing operations and to ship out completed pages, usually in a format specific to a particular kind of hard- or software.

Most device drivers are not separately loadable but have to be compiled into the ghostscript program although, since ghostscript 7.04, drivers can also be implemented as external programs communicating with the kernel via the IJS interface. If you want to change the set of drivers contained in your ghostscript executable you therefore usually have to recompile it.

Ghostscript Distributions

Ghostscript source code is basically distributed in two forms: as AFPL Ghostscript and as GNU Ghostscript. (There is also ESP Ghostscript which is based on GNU Ghostscript.) A GNU ghostscript distribution with a particular version number is usually a re-issue of the AFPL ghostscript distribution with that number but with less restrictions on commercial (re-)distribution, typically released about a year after the AFPL distribution. This was strictly true until about 2001. Since then, there have also appeared GNU ghostscript releases which contained bug fixes with respect to an AFPL distribution. In April 2002 GNU ghostscript 7.05 was released; this was not a re-issue of an AFPL ghostscript version but a ghostscript distribution from the current development branch, released immediately under the terms of the GNU General Public License. In November 2002, AFPL ghostscript 8.00 reverted to the previous policy of restricting the licensing terms of the most current distribution. I am not aware of any statement concerning the future license policy.

Ghostscript distributions can be found on a number of FTP servers. In addition, all free UNIX distributions I know of contain a compiled ghostscript distribution, usually with an extended set of device drivers.

More Information on Ghostscript

The main WWW resource for ghostscript is http://www.cs.wisc.edu/~ghost. It tells you what the current version of ghostscript is, how to obtain it, and what other programs and pieces of information are of interest in this context.

In addition, every ghostscript distribution contains extensive documentation.

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