Several options may be set in the postscript driver.
Syntax:
set terminal postscript {<mode>} {enhanced | noenhanced}
{color | monochrome} {solid | dashed}
{<duplexing>}
{"<fontname>"} {<fontsize>}
where <mode> is landscape, portrait, eps or default; solid draws all plots with solid lines, overriding any dashed patterns; <duplexing> is defaultplex, simplex or duplex ("duplexing" in PostScript is the ability of the printer to print on both sides of the same page---don't set this if your printer can't do it); enhanced activates the "enhanced PostScript" features (subscripts, superscripts and mixed fonts); "<fontname>" is the name of a valid PostScript font; and <fontsize> is the size of the font in PostScript points.
default mode sets all options to their defaults: landscape, monochrome, dashed, defaultplex, noenhanced, "Helvetica" and 14pt.
Default size of a PostScript plot is 10 inches wide and 7 inches high.
eps mode generates EPS (Encapsulated PostScript) output, which is just regular PostScript with some additional lines that allow the file to be imported into a variety of other applications. (The added lines are PostScript comment lines, so the file may still be printed by itself.) To get EPS output, use the eps mode and make only one plot per file. In eps mode the whole plot, including the fonts, is reduced to half of the default size.
Examples:
set terminal postscript default # old postscript
set terminal postscript enhanced # old enhpost
set terminal postscript landscape 22 # old psbig
set terminal postscript eps 14 # old epsf1
set terminal postscript eps 22 # old epsf2
set size 0.7,1.4; set term post portrait color "Times-Roman" 14
Linewidths and pointsizes may be changed with set linestyle.
The postscript driver supports about 70 distinct pointtypes, selectable through the pointtype option on plot and set linestyle.
Several possibly useful files about gnuplot's PostScript are included in the /docs/ps subdirectory of the gnuplot distribution and at the distribution sites. These are "ps_symbols.gpi" (a gnuplot command file that, when executed, creates the file "ps_symbols.ps" which shows all the symbols available through the postscript terminal), "ps_guide.ps" (a PostScript file that contains a summary of the enhanced syntax and a page showing what the octal codes produce with text and symbol fonts) and "ps_file.doc" (a text file that contains a discussion of the organization of a PostScript file written by gnuplot).
A PostScript file is editable, so once gnuplot has created one, you are free to modify it to your heart's desire. See the "editing postscript" section for some hints.
enhanced postscript
editing postscript