How can I specify a display

Question

When I run some programs over SSH  such as firefox  amp   I get an error   Error  no display specified    I would like to open many displays  still showing the stdout of each program    Initial Question  How can I specify the display to get a many-displayed program   Pablo Santa Cruz gives me the following code as a solution   I do not understand it     export DISPLAY yourmachine yourdomain com 0 0    firefox  amp    What are yourmachine and yourdomain com in the command

User · Answer

When you are connecting to another machine over SSH, you can enable X-Forwarding in SSH, so that X windows are forwarded encrypted through the SSH tunnel back to your machine. You can enable X forwarding by appending -X to the ssh command line or setting ForwardX11 yes in your SSH config file.

To check if the X-Forwarding was set up successfully (the server might not allow it), just try if echo $DISPLAY outputs something like localhost:10.0.

User · Answer

Try   export DISPLAY localhost 0 0

User · Answer

The way that X works is the same as the way any network program works  You have a server of some description  in this case  the X display server  which runs on a specific machine  and you have X clients  like firefox  that try to connect to that server to get their information displayed   Often  on  home  machines   the client and server run on the same box and there s only one server  but X is powerful enough that this doesn t need to happen  It was built with the server client separation built in from the start   This allows you to do such wondrous things such as log on to your box  in text mode  halfway around the planet  tell it that the display server is the box you re currently on and  voila  the windows suddenly start appearing locally   In order for a client to interact with a user  it needs to know how to find the server  There are a number of ways to do this  Many clients allow the -display or --displayoption to specify it   xeyes -display paxbox1 paxco com 0 0   Many will use the DISPLAY environment variable if a display isn t specifically given  You can set this variable like any other   DISPLAY paxbox1 paxco com 0 0  export DISPLAY   in  profile export DISPLAY paxbox1 paxco com 0 0   in your shell DISPLAY paxbox1 paxco com 0 0 firefox  amp    for that command  shell permitting    The first part of the DISPLAY variable is just the address of the display server machine  It follows the same rule as any other IP address  it can be a resolvable DNS name  including localhost  or a specific IP address  such as 192 168 10 55    The second part is X-specific  It gives the X  display   X server  number and screen number to use  The first  display number  generally refers to a group of devices containing one or more screens but with a single keyboard and mouse  i e   one input stream   The screen number generally gives the specific screen within that group   An example would be    ----------------------------------------   paxbox1 paxco com                          -----------------                                                                        ---------- ----    ---------- ----         Display  0         Display  1              ----------         ----------                                                           -----------                                Screen  0 0                                -----------                                -----------                                Screen  0 1                                -----------                                -----------        -----------             Screen  0 2        Screen  1 0             -----------        -----------             -----------        -----------             Screen  0 3        Screen  1 1             -----------        -----------             -----------        -----------              Keyboard            Keyboard              -----------        -----------             -----------        -----------                Mouse              Mouse                -----------        -----------           ---------------    ---------------                                                 ----------------------------------------    Here you have a single machine  paxbox1 paxco com  with two display servers  The first has four screens and the second has two  The possibilities are then   DISPLAY paxbox1 paxco com 0 0 DISPLAY paxbox1 paxco com 0 1 DISPLAY paxbox1 paxco com 0 2 DISPLAY paxbox1 paxco com 0 3 DISPLAY paxbox1 paxco com 1 0 DISPLAY paxbox1 paxco com 1 1   depending on where you want your actual windows to appear and which input devices you want to use

User · Answer

export DISPLAY yourmachine yourdomain com 0 0   firefox  amp

User · Answer

login to your server via  ssh -X root yourIP   edit  etc ssh sshd config file  and add this line to it   X11UseLocalhost no   Restart sshd  for CentOS  check your distribution    sbin service sshd restart   check your DISPLAY  echo  DISPLAY   you should see this  yourIP 10 0   Enjoy  firefox   for more info

User · Answer

Even i faced the same in CentOS 6 8   yum reinstall xorg    End your current session and open another session in tool like mobiXterm  Make sure session has X11 forwarding enabled in the tool

User · Answer

I faced similar problem today  So  here s a simple solution  While doing SSH to the machine  just add Ctrl - Y   ssh user ip address -Y   After login  type firefox  amp    And you are good to go

User · Answer

I through vnc to understand the X11 more. To specify the display to get a many-displayed program, export DISPLAY=IP:DisplayNum.ScreenNum

For example,

vncserver :2
vncserver -list
echo '$DISPLAY'=$DISPLAY 
export DISPLAY=:2  # export DISPLAY=IP:DisplayNum or export DISPLAY=:DisplayNum for localhost; So that can vnc connect and see the vnc desktop :2 if $DISPLAY is not :2.
echo '$DISPLAY'=$DISPLAY

User · Answer

Try installing the xorg-x11-xauth package

User · Answer

I ran into a similar issue  so maybe this answer will help someone   The reason for the Error  no display specified error is that Firefox is being launched  but there is no X server  GUI  running on the remote host  You can use X11 forwarding to run Firefox on the remote host  but display it on your local host  On Mac OS X  you will need to download XQuartz in order to use X11 forwarding  Without it  you won t have a  DISPLAY variable set  so if you try and echo  DISPLAY  it will be blank

User · Answer

Please do NOT try to set  DISPLAY manually when connecting over SSH  If you connect via SSH -X and  DISPLAY stays empty  this usually means that no encrypted channel could be established   Most likely you are missing the package xauth or xorg-x11-xauth  Try to install it on the remote machine using   sudo apt-get install xauth   or  sudo apt-get install xorg-x11-xauth   After that end and restart your SSH connection  Don t forget to use SSH -X so that X Window output is forwarded to your local machine   Now try echo  DISPLAYagain to see if  DISPLAY has been set automatically by the SSH demon  It should show you a line with an IP address and a port

[x11] How can I specify a display?

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