grub-mount [,OPTION/...] ,IMAGE1 /[,IMAGE2 /...] ,MOUNTPOINT/
Debug tool for filesystem driver.
Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options.
The full documentation for grub-mount is maintained as a Texinfo manual. If the info and grub-mount programs are properly installed at your site, the command
should give you access to the complete manual.