2PLOT: plot line - draw straight lines

Usage: plot line <x1> <y1> <x2> <y2> ... (normal mode)
       plot line [[<x>] <y1>...]         (list mode)

Normal mode: 
The command draws a line that connects the given points by straight line
segments.

List mode:
The command draws straight lines through the points of the given vector
expressions x, y1,... If no vector expressions are specified,
straight lines are drawn through the points of all list columns. If
the x-expression is omitted (i.e. if only a single expression, y1, is
given), the x-coordinates are taken from the x-column of the list.