1) In in existing linux system, I installed linux on a
16 GB USB-A. When I boot from USB-A it works.

2) I successfully copied the USB-A using dd command into USB-B.

3)When I boot from USB-B it goes into grub rescue.

and I get the following error.

error: file /media/disk/grub/i-386-pc/normal.mod not found

(USB- A is 16 GB and USB-B is 64 GB).

How to boot successfully from USB-B?
What I should do now with the grub rescue command in hand with me,
or anythng else?

The link is very general, not addressing my specific error.
Looking forward t a more prgrmatic solution. Thanks.

specific error is grub-rescue. The short of it your going to have to reinstall grub bootloader to the mbr of the usb.
Without know nothing about the partition layout of the usb or directories on usb it is just a guessing game. The link provided tells how to resolve the issue from the grub-rescue prompt
You can boot into you installed system mount your usb somewhere, run
If your installed system boots in efi mode, the will have to add to the above command line.

Thanks, for some light.
I am newbie, how to mount my usb somewhere, not clear you mean in
rescue mode?
When I boot to the usb, all I have is the grub rescue> prompt.
The usb device is sdb and has only only direcotry sdb1.

I wish to see the end of the tunnel, have been trying for more than a week

How did you do this, what program or commands? did you use an iso?
What was the dd command you used?
where /mnt would be the mount point assuming /dev/sdb1 is the correct drive/paritition for the usb.

1) I installed using iso through a bootable device onto USB-A

2) Then I inserted USB-A(16 GB) and a blank USB-B (64 GB) intended to
copy the from A to B through this command.
(Why I did not install onto USB-B like in USB-A is on a 64GB installation
is not working I tried with almost all options in the partion making, always
I got unable to create partition in whatever format, or partition size. All my
installations are in 32 bit pc)

sudo dd=if/dev/sdb conv=sync,bs=4M status=progress gzip -c > linux-mint.gz
(sdb is USB-A)

then,

gunzip -c linux-mint.gz |sudo of=/dev/sec bs=4M
(sdc is USB-B)

No error in.
Now when I boot from USB-B, the rescue grub> is coming.
USB-A is bootable, and working fine.

Thanks once again, and I am eagerly waiting for a solution.

why didn't you plug both usbs in at the same time and where the ? will be what usb-a and usb-b are respectivly?

assumimg the usb you won't to fix is sdb
This also assumes there is a /boot/grub/grub.cfg already exist on the usb.
the umount is in case the usb was automounted when plugged in.

You may have a bad usb. They do go bad eventually depending on how old they are.

Thanks again for the efforts. I did copy directly using your suggestion, but that did not make any difference. That was my attempt. They are not different.

I checked the /boot/grub/grub.cfg file exists.

I tried your second suggesion, I get the following error. This is not installing the grub, for the last command the reported error is as follows:

arasu@lihome:~$ sudo grub-install --boot-directory=/mnt/boot /dev/sdb
Unrecognized option `--boot-directory=/mnt/boot'
Usage: grub-install [OPTION] install_device
Install GRUB on your drive.

-h, --help print this message and exit
-v, --version print the version information and exit
--root-directory=DIR install GRUB images under the directory DIR
instead of the root directory
--grub-shell=FILE use FILE as the grub shell
--no-floppy do not probe any floppy drive
--force-lba force GRUB to use LBA mode even for a buggy
BIOS
--recheck probe a device map even if it already exists

INSTALL_DEVICE can be a GRUB device name or a system device filename.

grub-install copies GRUB images into the DIR/boot directory specfied by
--root-directory, and uses the grub shell to install grub into the boot
sector.

Report bugs to <bug-grub@gnu.org>.
arasu@lihome:~$

then it will be