I'm always making multiboot usb, so I can have all my t00ls/dignostics/pentesting/live distro/antivirus in one usb. So far I've found that using either xboot or yumi in Windows creates my multiboots no problems. However, I tried yumi in Linux, and it's a hit and miss. I've also tried multibootSys and others. And I really would like to not depend on a program to create multiboot usb. Therefore, I'm would like to get understanding of the boot process into every live distro, so I can write my own script and make them. My question here is: Could someone help explaining the file sctructure of either a multiboot or single boot usb flash drive. For example. The drives needs to have a MBR, of course, and set to active and boot. After that the either the grub or what ever boot manager takes control. Then I think there's the menu.lst file listing of all their distro and path... Usually, there are a few lines for every distro in this menu file. What are the necessary ones? and is it pointing the kernel for that distro? could someone with detail info on this process elaborate

A lot of useful info here. http://www.easy2boot.com/ if you want a massive multiboot. I think it is based on grub4dos so you could actually use it.


No, a usb flash or hard drive doesn't need a mbr. There are basically three ways. MBR. Compatible mbr/uefi and gpt.

Iso images are not created the same. There is so much variation in how they are made and meant to be use that no one single method can be used usually. Simple dd or 7z commands can create a lot of them. You already know that creators exist for some that work great for single use.

Only needs to be active if you have more than one partition usually. (some OS's may require this)

Starting with a system group you may find it easier to create usb's.

No they don't need to be set active/bootable as that is limited to windows.

What I generally do is install Grub to the MBR of the flash drive, then manually create a grub.cfg file (or menu.lst if using Grub Legacy).
With Grub2, you can boot 'some' iso files directly without doing anything else. Most of the major Ubuntus will work, many other systems will not. The directories and files on the iso are very different as pointed out above so there is no simple template to use. If you can't boot the iso file directly, you can extract the iso and copy it to a partition on the flash drive and create an appropriate entry for it in the Grub menu. This has worked for every Linux I have tried although it is more cumbersome that booting an iso directly. Using these methods I have put 26 Linux Live systems and bootable tools on a 16GB flash drive. I wrote some instructions for myself after finishing which are three pages long. If you want something that will create a multi-boot with a few mouse clicks, good luck. Too many variations and constant changes in Linux systems and tools for that to work for long.