usb stick is not recognizing in centos7 for Buildinig Bootable USB to install OS.

[rahulvishwa81]

question is that I want to make a USB Bootable for Linux Centos installation by "iso file". I format USB stick using following command.

dd bs=4M if=/path/to/CentOS-7-x86_64-DVD-1810.iso of=/dev/sdx status=progress oflag=sync

here i get boot prompt having menu about installation of Centos 7.

but after following commands

dd bs=4M if=redobackup-livecd-1.0.4.iso of=/dev/sdx status=progress oflag=sync

&

dd bs=4M if=win10.iso of=/dev/sdx status=progress oflag=sync

USB doesn't gets Boot Prompt for redo or windows installation boot prompt.

How to get prompt for windows and redo softwares.

[jlehtone]

(I would not use word "format", but) dd simply copies the bits in ISO file into the device, overwriting what the USB had. Therefore, if the content of redobackup-livecd-1.0.4.iso or win10.iso does not look like "bootable" to the system like the content CentOS-7-x86_64-DVD-1810.iso does, then system won't boot from the resulting USB.

We should not need to know what the redo and win10 images have, i.e. how they should be used. They are not a CentOS issue. Is the "win10" installer even supposed to give any "prompt", rather than blindly proceeding?


Anecdotally, I've had an official USB from Microsoft that did boot in legacy mode, but not in EFI mode. The apparent mistake was in the case of directory names, which should not make a difference on case-insensitive FAT32 system, but perhaps EFI-implementation in my motherboard was cutting corners.