tkinter TclError no display name and no DISPLAY environment variable

Question

I am running a simple python script in the server   import matplotlib pyplot as plt import numpy as np  x   np random randn 60  y   np random randn 60   plt scatter x  y  s 20   out png    path to store out file png  plt savefig out png  dpi 150    I try to use the command python example py in this server which has matplotlib 1 5 1 installed it fails with the error   Traceback  most recent call last     File  example py   line 7  in  lt module gt      plt scatter x  y  s 20    File   home USER  virtualenvs nnet lib python2 7 site-packages matplotlib pyplot py   line 3241  in scatter     ax   gca     File   home USER  virtualenvs nnet lib python2 7 site-packages matplotlib pyplot py   line 928  in gca     return gcf   gca   kwargs    File   home USER  virtualenvs nnet lib python2 7 site-packages matplotlib pyplot py   line 578  in gcf     return figure     File   home USER  virtualenvs nnet lib python2 7 site-packages matplotlib pyplot py   line 527  in figure   kwargs    File   home USER  virtualenvs nnet lib python2 7 site-packages matplotlib backends backend tkagg py   line 84  in new figure manager     return new figure manager given figure num  figure    File   home USER  virtualenvs nnet lib python2 7 site-packages matplotlib backends backend tkagg py   line 92  in new figure manager given figure     window   Tk Tk     File   usr local lib python2 7 lib-tk Tkinter py   line 1810  in   init       self tk    tkinter create screenName  baseName  className  interactive  wantobjects  useTk  sync  use   tkinter TclError  no display name and no  DISPLAY environment variable   What is happening here

User · Answer

I had this same issue trying to run a simple tkinter app remotely on a Raspberry Pi. In my case I did want to display the tkinter GUI on the pi display, but I want to be able to execute it over SSH from my host machine. I was also not using matplotlib, so that wasn't the cause of my issue. I was able to resolve the issue by setting the DISPLAY environment variable as the error suggests with the command:

export DISPLAY=:0.0

A good explanation of what the display environment variable is doing and why the syntax is so odd can be found here: https://askubuntu.com/questions/432255/what-is-display-environment-variable

User · Answer

Matplotlib chooses  Xwindows backend by default  You need to set matplotlib to not use the Xwindows backend    Add this code to the start of your script  before importing pyplot  and try again   import matplotlib matplotlib use  Agg     Or add to  config matplotlib matplotlibrc line backend  Agg to use non-interactive backend   echo  backend  Agg   gt     config matplotlib matplotlibrc   Or when connect to server use ssh -X remoteMachine command to use Xwindows   Also you may try to export display  export DISPLAY mymachine com 0 0   For more info  https   matplotlib org faq howto faq html matplotlib-in-a-web-application-server

User · Answer

I want to add an answer here that noone has explicitly stated with implementation  This is a great resource to refer to for this failure  https   matplotlib org faq usage faq html In my case  using matplotlib use did not work because it was somehow already set somewhere else  However  I was able to get beyond the error by defining an environment variable  export MPLBACKEND Agg This takes care of the issue  My error was in a CircleCI flow specifically  and this resolved the failing tests  One wierd thing was  my tests would pass when run using pytest  however would fail when using parallelism along with circleci tests split feature  However  declaring this env variable resolved the issue

User · Answer

You can solve it by adding these two lines in the VERY beginning of your  py script    import matplotlib matplotlib use  Agg     PS  The error will still exists if these two lines are not added in the very beginning of the source code

User · Answer

Another solution is to install Xvfb  and export your display to it  ie   disp  8 screen 0 geom 640x480x24 exec Xvfb  disp -screen  screen  geom 2 gt  tmp Xvfb log  amp    Then    export DISPLAY  8      example py

User · Answer

I also met this problem while using Xshell to connect Linux server   After seaching for methods  I find Xming   Xshell to solve image imshow problem with matplotlib   If solutions aboved can t solve your problem  just try to download Xming under the condition you re using Xshell  Then set the attribute in Xshell  SSH- tunnel- X11transfer- choose X DISPLAY localhost 0 0

User · Answer

In order to see images  plots and anything displayed on windows on your remote machine you need to connect to it like this   ssh -X user hostname   That way you enable the access to the X server  The X server is a program in the X Window System that runs on local machines  i e   the computers used directly by users  and handles all access to the graphics cards  display screens and input devices  typically a keyboard and mouse  on those computers   More info here

User · Answer

To add up on the answer  I used this at the beginning of the needed script  So it runs smoothly on different environments   import os import matplotlib as mpl if os environ get  DISPLAY                 print  no display found  Using non-interactive Agg backend       mpl use  Agg   import matplotlib pyplot as plt   Because I didn t want it to be alsways using the  Agg  backend  only when it would go through Travis CI for example

[python] _tkinter.TclError: no display name and no $DISPLAY environment variable

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