Calling up graphic programs in a chroot environment

Your requirement

You have installed a Linux system under the /test subdirectory, or mounted the root partition of another Linux system. With the chroot /test command you can ʻswitch in’ as usual and call programs. But the start of graphical programs fails, even when you set DISPLAY to :0.

The problem

Local programs communicate with your computer’s X server via a Unix socket in the /tmp/.X11-unix directory. In your chroot environment there is no access to this socket.

The solution

With a mount command you show the of the ʻouter’ computer’s /tmp/.X11-unix directory in the chroot cage:

root@linux# mkdir -p /test/tmp/.X11-unix
root@linux# mount --bind /tmp/.X11-unix /test/tmp/.X11-unix

They also allow access to the display for all local processes:

user@linux> xhost + local:

After calling chroot /test, set the DISPLAY variable in the inner system to :0, and you can then start graphical programs:

root@linux# chroot /test
root@linux# export DISPLAY=:0
root@linux# xterm

By the way: for security reasons a TCP connection via localhost is switched off by default in most distributions, otherwise instead of the above trick you could take the route via localhost. Enter xhost + localhost outside, and export DISPLAY=localhost:0 inside.