Where to get PostScript or PDF readers

Those listed here aren't necessarily the only ways to view the documents, especially for PostScript which is recognized by many printers. Some Unix systems may have viewers for all three of these formats already.

  PDF ps DVI
(virtually)
any platform
www.adobe.com    
Mac OS"
Mac OS X  
Mac OS X " OS X TeX users have an interest in this.
Windows" Ghostscript, Ghostview and GSview  

For new methods that may not be listed here, check at the bottom of this page: HTML Math Overview

Mac OS X

For a fairly comprehensive list of Mac OS X readers in general, see Native OS X Apps : Readers

It is possible now to have a Ghostscript based PostScript viewer running natively in OS X.
MacGhostViewX is available at Kiffe & Kiffe - TeX. The Ghostscript package is required to handle PostScript interpretation as MacGhostViewX is just a previewer that calls on ghostscript utilities to perform file conversion.

A shareware alternative that is easier to install is MacGhostView, which does not require separate installation of the Ghostscript package.

Ghostscript

Ghostscript provides a utility to convert PostScript files to PDF and other formats.
These pointers are for just about any platform where it is possible to compile C programs.

See /usr/local/share/ghostscript/{version}/lib/FontMap.GS for the names of fonts and the corresponding files that should be in the fonts folder in order to use them in PostScript output.

To run ghostscript from a command line, gs is the program, located by default at /usr/local/bin/gs

But to convert from ps to pdf, use the script ps2pdf, also located in /usr/local/bin/