In the case of an installed Linux, such as Debian/Ubuntu or derivatives, it is possible to edit the Grub config file like this:
sudo vi /etc/default/grub
and comment out this line:
#GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
and replace it with this line:
GRUB_CMDLINE_LINUX_DEFAULT=""
and then run
sudo update-grub
which will print lots of output during the subsequent boot process instead of a splash screen, black screen, or circle, etc.;
I would like to know how can I get it to print this debug for a live USB?
I edited this file on the live USB:
boot/grub/grub.cfg
and I was able to change the colors of the grub menu, but even if I remove the quiet splash
words from the vmlinuz
commandline, the boot process occurs with a blank screen, giving no output at all, no clue as to what is going on;
I also edited these files on the live Ubuntu 20.04 USB to remove quiet splash
but it still tries to boot with a blank screen:
syslinux.cfg
isolinux/txt.cfg
The problem is that once I select to boot Ubuntu from the live USB grub
menu, it accesses the USB for about 10 seconds (the USB has a LED indicating this), during which the screen is blank with no output, and then the boot process is canceled and it goes back to the Acer splash; now that is a separate question;
in order to help figure that out, I would like to turn on the verbose output during the boot process, for a live USB, just like for an installed Linux.
I looked to see if there is any verbose option that may help but didn't find one, and the Grub for an installed system seems to be somewhat different than these config files on the live USB.
e
to edit the grub menu entry at boot time, it is no longer necessary to guess which config file has to be edited; however even with the quiet splash removed, it doesn't print anything; hopefully there is an option or environment variable that can be set there to make it print something to give an idea why the boot from the live usb fails (the live usb boots fine on another laptop, the problem is on the acer aspire 515 and I need the verbose debug to try to figure it out)quiet
andsplash
are two separate parametersquiet
and try addingloglevel=4
and/orverbose
quiet
andsplash
removed, in a laptop that has ubuntu installed and can boot from a live ubuntu usb, it does print the debug during boot; in the acer aspire 515 which has only uefi shell and does not boot from a live ubuntu usb (only getting as far as the grub menu) the debug does not print; I addedloglevel=4
andverbose
with quiet removed and still no debug - but now I think that is because it fails before the debug starts; on the laptop where it works, the debug starts after about 10sec; in the one where it does not work, after about 10sec the boot is canceled