How can I install grub in my Flash Drive?

[bkpsusmitaa]

Hello!
I have a 16GB pendrive, with two ext4 partitions. I plan to run
Knoppix from the flashdrive. My pendrive in one computer is /dev/sdb
I am trying grub-install /dev/sdb
The device is mounted in /media/sdb1 and /media/sdb2
I am getting a grub-probe error.

I read the following section:
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If you want GRUB to put images under a directory other than /boot, you
need to specify the option --boot-directory. The typical usage is that
you create a GRUB boot floppy with a filesystem. Here is an example:

# mke2fs /dev/fd0
# mount -t ext2 /dev/fd0 /mnt
# mkdir /mnt/boot
# grub-install --boot-directory=/mnt/boot /dev/fd0
# umount /mnt
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In my other computer the drive is read as /media/sdc1 and sdc2
when I write: grub-install /dev/sdc
 or             : grub-install /dev/sdc1
I get:
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grub-install /dev/sdc
grub-probe: error: cannot find a device for / (is /dev mounted?).
grub-probe: error: cannot find a device for /boot/ (is /dev mounted?).
Could not find device for /boot: Not found or not a block device
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address@hidden:/home/knoppix# grub-install /dev/sdc1
grub-probe: error: cannot find a device for / (is /dev mounted?).
grub-probe: error: cannot find a device for /boot/ (is /dev mounted?).
Could not find device for /boot: Not found or not a block device.
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