-o filename

Specify where the output should be written.  Default: standard output.

-html

Generate HTTP header tags before outputting the image, e.g. image/gif

size width height pixels

Specify the size of the drawing and how many pixels per unit, in units.  Default pixels: 10 per unit.  This command must be the first command provided.

origin x y

Specify what coordinates are the lower left corner of the plot.  Or, rather, where the origin is relative to the lower left corner.  For example, if the lower left is (-3,-2), then use origin 3,2.

box x1 y1 x2 y2 color

Specify a filled rectangular region with opposite corners as specified.

line x1 y1 x2 y2 color

segment x1 y1 x2 y2 color

Draw a line segment from (x1,y1) to (x2,y2) of the color specified.

circle x y r color

Draw a filled circle with its center at (x,y), radius r and filled with color specified.

text x y color text

Draw text starting at (x,y) and moving right using color specified.

polygon x1 y1 x2 y2 ... color

Draw a filled polygon from point (x1,y1) to point (x2 y2) and so forth of the specified color.

polyline x1 y1 x2 y2 ... color

Draw a series of connected line segments of the specified color.

linewidth width

Change the line thickness for line drawing (box, circle, line, etc.)  A width of 0 or less means the minimum width (1 pixel).

linetype type

Change the line style, where type may be:  solid, dotted, dashed, or dotdash.