How to check if X server is running

Question

Is there any way to find out if the current session user is running an Xserver  under Linux     I v started off with things like   ps -e   grep X    but this doesn t work always  and one more thing I tried is checking the  DISPLAY variable  Are there any other ways to check this   EDIT  Some people suggested using the  DISPLAY variables but what if the user fiddles with this variable   what if he tries to do something and changes this variable and then when I check it  it no longer reflects an accurate state of the system   Is there no specific way to do this that will always return a correct answer    I found that it can be done programatically thus    include  lt X11 Xlib h gt   int main         exit XOpenDisplay NULL    0   1          gcc -o xprobe xprobe c -L usr X11R6 lib -lX11    But I am looking for a script way

User · Answer

1      netstat -lp grep -i x tcp        0      0   x11                                           LISTEN      2937 X           tcp6       0      0      x11                                        LISTEN      2937 X           Active UNIX domain sockets  only servers  unix  2        ACC       STREAM     LISTENING     8940     2937 X                tmp  X11-unix X0 unix  2        ACC       STREAM     LISTENING     8941     2937 X               tmp  X11-unix X0     2  nmap     nmap localhost grep -i x 6000 tcp open  X11

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First you need to ensure foundational X11 packages are correctly installed on your server   rpm -qa   grep xorg-x11-xauth   If not then  kindly install all packages    sudo yum install xorg-x11-xauth xterm   Ensure that openssh server is configured to forward x11 connections    edit file   vim  etc ssh sshd config  X11Forwarding yes   NOTE   If that line is preceded by a comment     or is set to no  update the file to match the above  and restart your ssh server daemon  be careful here     if you made an error you may lock yourself out of the server   sudo  etc init d sshd restart   Now  configure SSH application to forward X11 requests    ssh -Y your username your server your domain com

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I use  pidof X  amp  amp  echo  yup X server is running    pgrep and  DISPLAY are other options    Other considerations   su then  DISPLAY will not be set  Things that change the environment of the program running can make this not work   I don t recommand ps -e   grep X as this will find procX  which is not the X server

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if     DISPLAY     then        fi

User · Answer

I often need to run an X command on a server that is running many X servers  so the ps based answers do not work  Naturally   DISPLAY has to be set appropriately  To check that that is valid  use xset q in some fragment like  if   xset q  amp  gt  dev null  then     echo  quot No X server at   DISPLAY   DISPLAY  quot   gt  amp 2     exit 1 fi  EDIT Some people find that xset can pause for a annoying amount of time before deciding that  DISPLAY is not pointing at a valid X server  often when tcp ip is the transport   The fix of course is to use timeout to keep the pause amenable  1 second say  if   timeout 1s xset q  amp  gt  dev null  then

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You can use xdpyinfo  can be installed via apt-get install x11-utils

User · Answer

This is PHP script for checking    xsession    pidof X   if    xsession        echo  There is no active X session  aborting   n       exit      Similar command can be used in shell script too  like the pidof command

User · Answer

xprop -root  amp  gt   dev null       is my tried  amp  true command to test for an  X-able  situation  And  it s pretty much guaranteed to be on any system running X  of course  the command fails if not found anyways  so even if it doesnt exist  you can pretty much assume there is no X either   thats why I use  amp   instead of

User · Answer

One trick I use to tell if X is running is   telnet 127 0 0 1 6000  If it connects  you have an X server running and its accepting inbound TCP connections  not usually the default these days

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DISPLAY is the standard way   That s how users communicate with programs about which X server to use  if any

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The bash script solution   if   xset q  amp  gt  dev null  then     echo  No X server at   DISPLAY   DISPLAY    gt  amp 2     exit 1 fi   Doesn t work if you login from another console  Ctrl Alt F   or ssh  For me this solution works in my Archlinux      bin sh ps aux grep -v grep grep   usr lib Xorg  EXITSTATUS    if    EXITSTATUS -eq 0    then   echo  X server running    exit 1 fi   You can change  usr lib Xorg for only Xorg or the proper command on your system

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I wrote xdpyprobe program which is intended for this purpose   Unlike xset  xdpyinfo and other general tools  it does not do any extra actions  just checks X server and exits  and it may not produce any output  if  -q  option is specified

[linux] How to check if X server is running?

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