psdir

The set psdir <directory> command controls the search path used by the postscript terminal to find prologue.ps and character encoding files. You can use this mechanism to switch between different sets of locally-customized prolog files. The search order is

      1) The directory specified by `set psdir`, if any
      2) The directory specified by environmental variable GNUPLOT_PS_DIR
      3) A built-in header or one from the default system directory
      4) Directories set by `set loadpath`