If GNUTERM is defined, it is used as the name of the terminal type to be used. This overrides any terminal type sensed by GNUPLOT on start up, but is itself overridden by the .gnuplot (or equivalent) start-up file (see help start-up), and of course by later explicit changes.
On Unix and MS-DOS, GNUHELP may be defined to be the pathname of the HELP file (gnuplot.gih). On VMS, the symbol GNUPLOT$HELP should be defined as the name of the help library for gnuplot.
On Unix, HOME is used as the name of a directory to search for a .gnuplot file if none is found in the current directory. On MS-DOS, GNUPLOT is used. On VMS, SYS$LOGIN: is used. See help start-up.
On Unix, PAGER is used as an output filter for help messages. SHELL is used for the shell command.
On MS-DOS, COMSPEC is used for the shell command.