The show version command lists the version of gnuplot being run, its last
modification date, the copyright holders, and email addresses for the FAQ,
the gnuplot-info mailing list, and reporting bugs–in short, the information
listed on the screen when the program is invoked interactively.
Syntax:
show version {long}
When the long option is given, it also lists the operating system, the
compilation options used when gnuplot was installed, the location of the
help file, and (again) the useful email addresses.