### Environment variables

The environment variables must be defined before gnuplot is executed; how to do so depends on your operating system.

         FIT_LOG

changes the name (and/or path) of the file to which the fit log will be written from the default of `"`fit.log`"` in the working directory. The default value can be overwritten using the command set fit logfile.

         FIT_SCRIPT

specifies a command that may be executed after an user interrupt. The default is replot, but a plot or load command may be useful to display a plot customized to highlight the progress of the fit. This setting can also be changed using set fit script.