Info Catalog
grub: check_signatures
grub: Special environment variables
grub: cmdpath
15.1.3 chosen
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When executing a menu entry, GRUB sets the CHOSEN variable to the title
of the entry being executed.
If the menu entry is in one or more submenus, then CHOSEN is set to
the titles of each of the submenus starting from the top level followed
by the title of the menu entry itself, separated by '>'.