I want to customize a little my GRUB 2 bootloader, so I'm asking how can I set a variable equal to the output from a command in GRUB2?

I am interested to pass the output of [`date`](http://members.iinet.net/~herman546/p20/GRUB2%20CLI%20Mode%20Commands.html#date) command to a variable. Moreover, how can I retain only the time or hour in that variable?