3. Global Variables
  
  
  3.1 Getting information about polymake output
  
  3.1-1 InfoPolymaking
  
  > InfoPolymaking__________________________________________________info class
  
  If  set to at least 2, the output of polymake is shown. At level 1, warnings
  are shown. This is the default. And at level 0, the polymake package remains
  silent.
  
  3.1-2 POLYMAKE_LAST_FAIL_REASON
  
  > POLYMAKE_LAST_FAIL_REASON__________________________________global variable
  
  Contains a string that explains the last occurence of fail as a return value
  of Polymake (2.5-1).
  
  
  3.2 Variables for system interaction
  
  The  variables  for  interaction  with  the system are contained in the file
  environment.gi.  Each  of these variables has a function to set it, see 1.2.
  If  POLYMAKE_COMMAND  or  POLYMAKE_DATA_DIR are set at startup, they are not
  overwritten.  So  if  you  don't  want  (or don't have the rights) to modify
  environment.gi, you can set the variables in your .gaprc file.
  
  3.2-1 POLYMAKE_COMMAND
  
  > POLYMAKE_COMMAND___________________________________________global variable
  
  This variable should contain the name of the polymake program in the form as
  returned      by      Filename      So      a      probable     value     is
  Filename(Directory("/usr/local/bin"),"polymake").
  
  3.2-2 POLYMAKE_DATA_DIR
  
  > POLYMAKE_DATA_DIR__________________________________________global variable
  
  In  this  directory the files for polymake will be created. By default, this
  generates a temporary directory using DirectoryTemporary
  
  3.2-3 POLYMAKE_CLIENT_PATHS
  
  > POLYMAKE_CLIENT_PATHS______________________________________global variable
  
  A  list  of  directories  where  polymake's the stand-alone clients live. By
  default, DirectoriesSystemPrograms is used.