GRUB USB option

Gigabyte GB-BXBT-1900 mini PC with Ubuntu 16.04.3 LTS operating system. Recent install. Probably could use some install components. I'd like to boot LinuxCNC from USB. BIOS no legacy boot and only boot order. Desktop tool bar shows USB (sdb1) device mounted. Not showing USB in GNU GRUB presently. Is a terminal, bash or grub and case sense prompt to enable GNU GRUB menu with USB option? Is or a download?

Plug your USB drive in.
Boot the computer
At the grub screen press c for command line.

type the following
ls
On my machine I get the following: (hd0) (hdo,msdos5) (hd0, msdos1) (hd1) (hd1,msdos1). hd0 is my HDD hd1 is my usb stick If you don't get a reference to your usb stick, which should be be hd and a number one more than your hdd, eg if you have 2 hdds the usb stick should be hd3
Type the following
ls (hd1)
On my machine I get the following: Filesystem type iso9660 - Lable `Debain Wheezy 20150905-22:03`
Plus 2 more lines, the first one is the important one
Type the following
insmod iso9660
insmod chain
set root=(hd1)
chainloader (hd1)+1
boot

This should bring up the Linuxcnc boot screen
Make your choice and boot

This is a good reference:
wiki.gentoo.org/wiki/GRUB2/Chainloading#Another_bootloader
You would have to add:
insmod iso9660
root (hd1)
chainloader (hd1)+1

The insmod part_msdos line should be able to be removed.

But you should get the idea.

Hopefully this should work, if it does or doesn't work report back.

My bootloader following:

' GNU GRUB version 2.02~beta2-36ubuntu3.12

grub> ls
(hd0) (hd0,msdos5) (hd0,msdos1) (hd1) (hd,msdos1)
grub> ls (hd1)
Device hd1: No known filesystem detected - Sector size 521B - Total size 7554758KiB '

No file system. Can I proceed? Is next?

grub> chain insmod

Is this going to work?

I don't think so, you need to see the message saying grub has found a file system.
When you wrote the image to the usb stick you used some thing like this. Assuming sdb is your usb stick under linux

dd if=pathtolinuxcncimage of=/dev/sdb bs=1M

Some have used sdb1 instead of sdb and have been unable to boot.

I didn't bash image to disk. Downloaded Ubuntu 16.04.3 LTS ISO from Ubuntu Webpage, C drive, plugged in external USB stick, opened Rufus utility and made bootable file.

Same to make LinuxCNC ISO bootable.

I could probably change boot order of BRIX and prioritize it. Default would boot LinuxCNC. I was trying to avoid changing BIOS boot order except if legacy boot but it appears no legacy boot. Opening my BIOS doesn't respond sometimes and have to trip or reset it's terminal or battery. Maybe BIOS not intercepted timely. That's advantage of legacy boot. Consequence GRUB USB. I could update BIOS utility if available. I haven't located an update from American Megatrends Inc (AMI) (Aptio) Web Page. Gigabyte has an update utility named Q-Flash but not sure if includes legacy boot. I might give it a try.

Before no Ubuntu OS with BRIX, no memory and RAM. Justed booted Debian LinuxCNC and appeared okay. After power off Debian and attempting to boot again terminal or grub couldn't find device and probably not mounted. Would prompting mount have to get done every time rebooting or is mount installable? Could it be if installing Debian LinuxCNC with a Windows OS and using it's devices? Does it matter if a no OS, only bootable install and just no default chosen drives and self name? LinuxCNC might default it's devices at end of install. I could install with a Linux OS and have a Chromebook too if helpful just for installation purposes.

Any other ideas?

I'm at a bit of a loss as too what you want to do.

Do you want to install Linuxcnc, or boot Linuxcnc from USB all the time or have Ubuntu and Linuxcnc installed on the same disk and have the choice between booting Ubuntu or Linuxcnc ?

The BRIX mini PC has an internal hard drive, RAM and the Ubuntu 16.04.3 LTS installation. This is the computer I'm trying to boot USB with GRUB.

The USB device, former .iso, with Ubuntu 16.04.3 LTS made bootable with Rufus utility appears okay. This is the very OS with Firefox browser I access LinuxCNC Forums. As indicated when plug-in USB stick, Ubuntu desktop, left screen, tool bar and show auto mount. It opens okay. I copied a .pdf file to the USB and it appears okay.

Could Rufus utility write an .iso and store it's filesystem differently? Is somewhere else to recover such filesystem and is it requirement with insmod?

blkid and sudo fdisk -l show /dev/sdb1 at my terminal.

The USB stick LinuxCNC is already bootable from Rufus utility.

Please, primarily I'd like to get USB into GRUB menu. Is another way with terminal or grub? Anyhow, boot the USB stick LinuxCNC.

Alternatively, would be Ubuntu and LinuxCNC on one hard drive and I'd guess a virtual box. Supposedly, LinuxCNC doesn't advice it but I've seen an individual on such as YouTube instruct installation.

Is any other direction to boot USB stick LinuxCNC with my configuration?

unix.stackexchange.com/questions/106969/...k-cd-dvd-flash-drive

"Optical disks almost always have either ISO 9660 or UDF filesystems on them (they're designed for the slow-as-molasses seek times of these devices)", as stated carot 2.

"There are 2 types of media that you'll typically see when dealing with CDs or DVDs. The type iso9660 is what is typically used for CDROMs. So mounting a CD your command would be fine", as stated carot 3.

My terminal.
sudo file -s /dev/sda1
/dev/sda1: Linux rev 1.0 ext4 filesystem data, UUID=....

Is it this type of filesystem?

askubuntu.com has some options. Rufus utility might have a particular file unrecognized to Ubuntu regardless bootable. I guess some had such experience with UNetbootin. I could probably make a boot disk with my Ubuntu terminal if it makes file recovery any more accessible and GRUB USB. It appears are some variations to script a USB partition to GRUB.

Follow the directions here to make a bootable usb device.

linuxcnc.org/docs/2.7/html/getting-start...to_a_bootable_device

Then follow the instructions I gave in my first post to boot the usb stick.

sda will be your first disk, 9 times of 10 that will be your harddisk or ssd.

Here is some information on dual booting 2 Linux distributions. There is no need to use virtual box