"No X11 DISPLAY variable" - what does it mean?

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I am trying to install a Java application on my Linux machine (Slackware).

I have received the following error, and I do not understand it.

Could you advise me how to approach the problem? Thank you.

Here is what I get: (I see that some X11 DISPLAY variable needs to be set, but what value should I give it and how?)

~$ java -jar gate-5.0-beta1-build3048-installer.jar
- ERROR -

java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
at java.awt.GraphicsEnvironment.checkHeadless(Graphic sEnvironment.java:159)
at java.awt.Window.<init>(Window.java:407)
at java.awt.Frame.<init>(Frame.java:402)
at net.sourceforge.mlf.metouia.borders.MetouiaDotsBuf fer.<init>(MetouiaDotsBuffer.java:105)
at net.sourceforge.mlf.metouia.borders.MetouiaDots.<i nit>(MetouiaDots.java:66)
at net.sourceforge.mlf.metouia.borders.MetouiaToolBar Border.<init>(MetouiaToolBarBorder.java:49)
at net.sourceforge.mlf.metouia.MetouiaLookAndFeel.ini tComponentDefaults(MetouiaLookAndFeel.java:241)
at javax.swing.plaf.basic.BasicLookAndFeel.getDefault s(BasicLookAndFeel.java:130)
at javax.swing.plaf.metal.MetalLookAndFeel.getDefault s(MetalLookAndFeel.java:1591)
at javax.swing.UIManager.setLookAndFeel(UIManager.jav a:537)
at javax.swing.UIManager.setLookAndFeel(UIManager.jav a:581)
at com.izforge.izpack.installer.GUIInstaller.loadLook AndFeel(GUIInstaller.java:373)
at com.izforge.izpack.installer.GUIInstaller.<init>(G UIInstaller.java:116)
at sun.reflect.NativeConstructorAccessorImpl.newInsta nce0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInsta nce(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newI nstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Construc tor.java:513)
at java.lang.Class.newInstance0(Class.java:355)
at java.lang.Class.newInstance(Class.java:30
at com.izforge.izpack.installer.Installer.main(Instal ler.java:62)
11 Answers

If you're on the main display, then

export DISPLAY=:0.0

or if you're using csh or tcsh

setenv DISPLAY :0.0

before running your app.

Actually, I'm surprised it isn't set automatically. Are you trying to start this application from a non-graphic terminal? If not, have you modified the default .profile, .login, .bashrc or .cshrc?

Note that setting the DISPLAY to :0.0 pre-supposes that you're sitting at the main display, as I said, or at least that the main display is logged on to your user id. If it's not logged on, or it's a different userid, this will fail.

If you're coming in from another machine, and you're at the main display of that machine and it's running X, then you can use "ssh -X hostname" to connect to that host, and ssh will forward the X display back. ssh will also make sure that the DISPLAY environment variable is set correctly (providing it isn't being messed with in the various dot files I mentioned above). In a "ssh -X" session, the DISPLAY environment variable will have a value like "localhost:11.0", which will point to the socket that ssh is tunnelling to your local box.

Are you running this from within an X11 environment? You can use a terminal window, but it has to be within X (either after a graphical login, or by running startx).

If you're already within a graphical environment, try export DISPLAY=:0 for bash like shells (bash, sh, etc) or setenv DISPLAY :0 for C shell based shells (csh, tcsh, etc)

If you've connected from another machine via SSH, you use the -X option to display the graphical interface on the machine you're sitting at (provided there's an X server running there (such as xming for windows, and your standard Linux X server).

There are many ways to do this. I did something below convenient to me and always works fine.

  1. On your remote server, make sure to install xorg-x11-xauth, xorg-x11-font-utils, xorg-x11-fonts.
  2. Run the Xming Server on you local desktop
  3. On putty, before ssh to the server, enable the X11 forwarding and set the display location to localhost:0.0
  4. On the server, .Xauthority file is generated and notice that the DISPLAY variable is already set.

    $ xauth list

    $ xauth add

To test it, type xclock or xeyes

Note: To switch user, copy the .Xauthority file to the home directory of the respective user and also export the DISPLAY variable from that user.

Set the display mode is fine and also make sure that the apache Jmeter start from your USER mode, DON'T run in ROOT user.

$ cd /home/USER/apache-jmeter-5.5/
$ ./jmeter
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