I need to shutdown a server at a specific hour a few days from now. The command `shutdown <https://linux.die.net/man/8/shutdown>`_ allows to specify the hour but not the day so that can't be used. It also allows to specify a number of minutes from "now" which implies computing that value. So the following can be used:
sudo shutdown -h +$(($(($(date -d 'yyyy-mm-dd hh:mm:ss' +"%s") - $(date +"%s"))) / 60))
I guess there is also the `at <https://linux.die.net/man/1/at>`_ command, though.