Is there any way to assign or get the DISPLAY variable of the new X server?

[CicadaSeventeen]

When not using --hostdisplay, new X server gets a new DISPLAY variate. I try using --env DISPLAY=:100 to assign the DISPLAY variate of the new X server, but that not work. Or else, it is OK not to assign that, however, instead, to know the DISPLAY variate of the new X server. If I open a terminal like x11docker --exe xterm or x11docker -- x11docker/xfce xfce4-terminal, it is OK to use env|grep DISPLAY, but it does not work otherwise. So if there are anyway to get. Now the only way working I have find is like x11docker --exe "env|grep DISPLAY > _FILENAME_ ; xterm" if I do not run program of any image. For running programs in images x11docker -- x11docker/xfce "env|grep DISPLAY > _FILENAME_ ; xfce4-terminal" does not work at all, showing cannot find such command. So, if there any way to control, even if just to know, the DISPLAY variate of the new X server?

[mviereck]

Compare x11docker --help:

Output of parseable information on stdout:
  Get output e.g. with:  read xenv < <(x11docker --showenv x11docker/check)
     --showenv         Print new $DISPLAY, $XAUTHORITY and $WAYLAND_DISPLAY.

X and Wayland special configuration:
     --display=N       Use display number N for new X server.

[CicadaSeventeen]

Thanks so much.

[mviereck]

x11docker -- x11docker/xfce "env|grep DISPLAY > FILENAME ; xfce4-terminal" does not work at all, showing cannot find such command.

To run multiple commands, try with sh -c '...'

x11docker -- x11docker/xfce sh -c "env|grep DISPLAY > _FILENAME_ ; xfce4-terminal"