Psdir

The set psdir 4#4directory5#5 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`