Each user has environment variables. XDG_RUNTIME_DIR
is most likely not defined in root user's environment or is being overwritten as empty.
To fix it in your current shell (temporarily), login as root and type export XDG_RUNTIME_DIR="/run/user/1000"
To fix it every time root logs in you can define it in ~root/.profile
.
Just add the line export XDG_RUNTIME_DIR="/run/user/1000"
at the bottom of the file. Then either source ~/.profile
or logout & login again.
You can verify which environment variables are defined in the current shell, type env
, or a specific one with env | grep XDG_RUNTIME_DIR