Bug#741074: gnuplot-nox: By default no plots (or error messages) are generated

[Dima Kogan]

Package: gnuplot-nox
Version: 4.6.5-1
Severity: normal

Hi.

When using gnuplot-nox to make plots WITHOUT setting up a terminal,
gnuplot starts up with the "unknown" terminal. Any plot command then
results in no output AND no error messages. Example:

  dima at shorty:~$ dpkg -l gnuplot-nox
  Desired=Unknown/Install/Remove/Purge/Hold
  | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
  |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
  ||/ Name                   Version          Architecture     Description
  +++-======================-================-================-==================================================
  ii  gnuplot-nox            4.6.5-1          amd64            Command-line driven interactive plotting program. 

  dima at shorty:~$ ls -l ~/.gnuplot
  ls: cannot access /home/dima/.gnuplot: No such file or directory

  dima at shorty:~$ gnuplot
  
          G N U P L O T
          Version 4.6 patchlevel 5    last modified February 2014
          Build System: Linux x86_64
  
          Copyright (C) 1986-1993, 1998, 2004, 2007-2014
          Thomas Williams, Colin Kelley and many others
  
          gnuplot home:     http://www.gnuplot.info
          faq, bugs, etc:   type "help FAQ"
          immediate help:   type "help"  (plot window: hit 'h')
  
  Terminal type set to 'unknown'
  gnuplot> plot x
  gnuplot> ^D


So no plot was generated, and no error message came through either. This
is a highly non-obvious failure, especially when using gnuplot
indirectly (with feedgnuplot, say). I think gnuplot should produce an
error message if trying to plot with an 'unknown' terminal, and I'll
suggest that upstream. Until then, I propose to set a default terminal
in

 /usr/share/gnuplot/gnuplot/4.6/gnuplotrc

so that we don't come up with the 'unknown' terminal. I suggest the
'dumb' terminal. This likely isn't what the user wants (although maybe
it IS, since they installed 'gnuplot-nox'), but it would be a highly
obvious behavior.