during some recent update of my laptop, sage ceased to show pictures from command-line.
That is, for instance:
sage: plot(x^2, [x,0,1])
"Launched png viewer for Graphics object consisting of 1 graphics primitive"
Except no png viewer is launched (it used to start external image-viewer).
The png-files are properly created in the appropriate tmp folder.
Also starting pdf viewer works:
... starts a pdf viewer with x^2 typeset in tex.
I tried to check the viewer and everything seems to be OK:
sage: from sage.misc.viewer import viewer
And, when I try xdg-open in a shell (i.e., outside of sage), then it open correctly both png and pdf files.
Any ideas? It starts to be quite annoying (the only workaround I found is to save the plot to a png ...).
My system is ubuntu 15.10,
SageMath Version 6.10, Release Date: 2015-12-18 -- obtained from file
But it did not work with sage 6.8 and 6.7 either. I'm not sure but I believe it worked with ubuntu 15.04 (and some previous version of sage).
Thanks in advance for any suggestion,