I have a thumb drive

subjected to dd command:

It works as a bootable thumbdrive to install Debian 9.


Now, on a CentOS 7 terminal,

I found this:


But

parted seems to be completely confused by the content.

Is parted inferior to fdisk?

This has a good explanation:
https://superuser.com/questions/1194...k-gdisk-parted

I prefer to use command line tools, most GUI tools use them underneath anyway, so I cut out the overhead.

I've found fdisk & cfdisk work well for me.

That's probably a hybrid USB - open to interpretation.
For many years I avoided parted, but when gpt became the "go-to" structure for me, fdisk was useless, so I switched to parted, and got used to it eventually. With the re-write of fdisk 18 months or so ago, it now is usable again, but I tend not to use it a lot except for listing.

So, use what you're comfortable with - both are "right".

The discrepancy between fdisk and parted means that I am not ready to believe what they say about a disk
that has been subjected to a dd command. I know
the thumbdrive is 16 GB when I bought it. The deeper question is: what does dd do beyond copy blindly
from source A to destination B. How does it affect the partition table? That is the fundamental question.

I knew nothing the diff between GPT vs MBR (or msdos) until recently. Strange thing is that
I was able to manage a few laptops/desktops, each with a few OSes, some UEFI, some non-UEFI,
some grub1, and some grub2. Partitioning of the disks are always with gparted.

I guess I have always been lucky.

Anyway, I trusted gparted a lot (especially that comes with the LiveDVD of latest Linux Mint).
I hope gparted can do all what gdisk can do eventually.

"dd" does as it is requested by the user. Sometimes it is even what the user thinks they requested.

A USB thumb-drive is not a "real" disk. All of the tools work fine with "real" disks.
Be careful to define your requirements precisely - to yourself as well as to the rest of the world.

I agree with syg00. Your correct dd just copies byte for byte the contents of the file to the USB drive. However, firmware-9.9.0-amd64-netinst.iso is a hybrid ISO which is basically a CD/DVD that contains a MBR.

I believe parted is examining the filesystem which is ISO9660 but fdisk just looks at the MBR therefore your seeing a perceived discrepancy.

https://wiki.syslinux.org/wiki/index...itle=Isohybrid

In another example if you use dd to create an image of a smaller drive and then copy it to a larger capacity drive, the larger drive will appear to be the same size as the smaller one because the MBR/UEFI is the same regardless of its actual "physical" size. You have to resize the partitions to use the empty space.

By deleting the MBR and recreating a new partition table and partitions you can "restore" the USB drive back to "normal".