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 start-up) and, of course, by later explicit changes.
On Unix, AmigaDOS, AtariTOS, MS-DOS and OS/2, GNUHELP may be defined to be the pathname of the HELP file (gnuplot.gih).
On VMS, the logical name gnuplot$HELP should be defined as the name of the help library for gnuplot. The gnuplot help can be put inside any system help library, allowing access to help from both within and outside gnuplot if desired.
On Unix, HOME is used as the name of a directory to search for a .gnuplot file if none is found in the current directory. On AmigaDOS, AtariTOS, MS-DOS and OS/2, gnuplot is used. On VMS, SYS$LOGIN: is used. See help start-up.
On Unix, PAGER is used as an output filter for help messages.
On Unix, AtariTOS and AmigaDOS, SHELL is used for the shell command. On MS-DOS and OS/2, COMSPEC is used for the shell command.
On MS-DOS, if the BGI interface is used, the variable BGI is used to point to the full path of the BGI drivers directory. Furthermore, SVGA is used to name the Super VGA BGI driver in 800x600 resolution and its mode of operation as 'Name.Mode'. E.g., if the Super VGA driver is C: \TC \BGI \SVGADRV.BGI and mode 3 is used for 800x600 resolution, then use 'set BGI=C: \TC \BGI' and 'set SVGA=SVGADRV.3'.
FIT_SCRIPT may be used to specify a gnuplot command to be executed when a fit is interrupted—see fit. FIT_LOG specifies the filename of the logfile maintained by fit.