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Is it possible to start ubuntu from a USB drive without actually booting from it?

Sorry this question did not seem clear. I have just placed ubuntu onto a 4GB flash drive. the computer I was going to use it on cannot boot from a USB port. Only a CD drive, HDD or floppy.

so, can I get ubuntu started from the USB flash drive I have just created or do I need to create a CD?

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It's not clear what you are asking. Please elaborate. – edwin Jul 11 '13 at 20:15
I think you have your terminology all mixed up. Booting IS the process of starting an OS – hmayag Jul 11 '13 at 20:15
I'm not sure I have. Booting is starting the computer. Back when I started the computers could not start unless they had a program but we could not put in a program unless it was started ... thus, lifting ones self up by one's own bootstraps. We'd start with a loader which then started an OS of sorts – user174444 Jul 11 '13 at 20:23
yes the BIOS is there to look for a program and start the load process for the program into memory then hand over the execution address to the processor, usually this is the OS but it doesn't have to be. After all an OS is 'just' another program. <br/> Sorry, I forget what the computer was now it was a long time ago, I was at school, it was in a data centre and it was all very exciting as they explained the process. It's funny how these things stick in my mind. – user174444 Jul 12 '13 at 3:46
up vote 0 down vote accepted

If your computer cannot boot from usb, first be sure you checked the bios settings and that usb boot is enabled. It's not entirely clear what your purpose is.

If you already have Ubuntu installed, you could use grub to boot the usb -- provided it's a full install on a usb, not the live media. You would just start Ubuntu normally, stick in the usb, then sudo update-grub in a terminal and it will add the usb drive to the boot menu.

If you are just trying Ubuntu for the first time, the easiest thing by far is just to make the cd and boot from that. But it is possible to install another bootloader to the usb, such as Plob, that can boot machines that don't have bios support for usb booting.

Most computers made in the past 5 years should be able to boot from usb. If your goal is to a distro in your pocket than you should be safe with a standard live media. (And best to make it persistent as well.)

If you think that you may need to use it on unknown computer that can't boot from usb, then definitely look into Plop.

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The only boot options are the three I described in the initial question. It is for the first time but I wanted to carry an unbuntu 'computer' around on my flash drive and boot at church to demo it with open office on one of their computers that struggling running windows but they are reluctant to try anything else. -- I wanted to run it from the USB drive to prepare it with some of their presentations before taking it in, I'm not sure I can add some presentations to a CD image, although I've not tried and it may be easier that I anticipate. -- but thanks, I will check out Plob... – user174444 Jul 11 '13 at 21:45
Now that I know your goal, I edited the answer a little to include info from your comment. Good luck with your project. If the answer helped you, please upvote or accept. :) – chaskes Jul 11 '13 at 21:51
Thank you. I'll read the Plop page you've suggested for other computers. For my computer, I cannot set it to USB boot in the BIOS but hitting F11 with the USB drive plugged in, I'm asked for a boot device and can select USB, how ever I then get a grey screen with a symbol that seems to indicate that it won't work with my USB keyboard ... Sigh! This PC was thrown together from three old ones being thrown away and I've had the same problem before, USB k/b wouldn't work during install but is fine now that the OS is installed and running from the HDD. At least I've now checked the USB drive. – user174444 Jul 11 '13 at 22:57

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