I get that, when -I- type a "c", then <Tab>, to a Grub boot menu (see attached picture)
But -I- find it much more expedient to do a
DDG for grub prompt
Someday, I may try doing things with (maybe /boot/grub/grub.cfg) to reproduce this.
https://help.ubuntu.com/community/Grub2/Troubleshooting
I get a LOT longer list of commands, so maybe investigate
core.img
p.s. Could you please mark
this/
that as 'Solved'? Thank you.