< look at the plotutil(1) documenation, info file, and such for information on the plot(1) command and the GNU plotutils. Several related pages are at http:www.gnu.org/software/plotutils has a web page.
http://www.fsf.org/software/plotutils/plotutils.html has a web page.
http://ftp.gnu.org/pub/gnu/plotutils/plotutils-2.4.1.tar.gz has a source tarball.