Copy Ubuntu Install from Internal Drive to Bootable USB that boots BIOS or UEFI
An external drive can easily be copied to USB using dd or Disks 'Create Disk Image" / "Restore Disk Image".
However these methods only create a drive that boots in the same BIOS or UEFI mode as the original.
It is also handy to have a FAT32 or NTFS Data partition that can save data from the computer it was plugged into.
The question is: How can I create a bootable USB drive that is a clone of my desktop and boots in either BIOS or UEFI mode.
It should also have a data partition that can store data from Windows and Apple computers.