linux - Cron with notify-send

Question

I need to show a notification from a cron job. My crontab is something like:

$ crontab -l
# m h  dom mon dow   command
  * *   *   *   *    Display=:0.0 /usr/bin/notify-send Hey "How are you"

I checked /var/log/syslog and the command is actually executed every minute but it doesn't pop up the notification. Can anybody help me understand why?

Answer 1

I use i3 on Ubuntu 18.04. My way to solve this is:

* * * * * XDG_RUNTIME_DIR=/run/user/$(id -u) notify-send Hey "this is dog!"

Edit 2020: I still use it on Ubuntu 20.04.