"Can't open display" with centos7 minimal installation

[yeongjet]

St running successful in centos7 with gnome ,but I run it fail with minimal installation after installing X window system, libX11, libXft,libXext which it require and it display "can't open display".
There are some situations in minimal

1. run
   DESKTOP=:0.0
sudo X
   X server start successful.
   2.startx
   It said ~/xauth's some files not found
   3.'systemctl isolate graphical.target'
   It said 'PolicyKit daemon disconnected from the bus,We are no longer a registered authentication agent'
   4.run xclock(an X11 program) successful
   What should I do?

[setkeh]

What happens if you run

DISPLAY=:0 st

That should force it to connect to display 0

also can you paste the output from

echo $DISPLAY

and

cat /var/log/Xorg.0.log

And possibly your xorg.conf that may give us some more info as to what you issue is :)

[l3pp4rd]

thanks for your help @setkeh
@Kcetry that is unusual, DISPLAY should always default to 0. Maybe the user you start st with, does not have these defaults loaded into his shell environment.

[yeongjet]

Thanks for help! @setkeh @l3pp4rd I have solved this problem.The reason is that I haven't install window manager which X server use when it start.Then,I installed dwm and st,also,edited the ~/.xinitrc,and run startx successful.I have to said,the suckless's software is slim but powerful,Thanks again. ^.^

[l3pp4rd]

glad you solved it @Kcetry never had any crash with this software. you can also use slim as login manager and dmenu to launch applications.

[setkeh]

Im glad you solved it mate :) Glad to lend a hand good luck :D