How to check for actual USB capacity in Linux terminal

Install F3

Ubuntu, Linux Mint, Elementary OS and Debian sudo apt install f3 **Fedora ** sudo dnf install f3 Arch yaourt f3

Checking Capacity

Use Gparted or Disk Manager to see the capacity of the Pen or Flash drive. Or use [c]lsblk[/c] on terminal lsblk

Testing for the Actual Capacity

f3write f3write /media/flash-drive-mount-point **Replace [c]flash-drive-mount-point[/c] with the correct drive mount point The above command will start writing on the drive with 1GB files named Nh2w when N is an number.

f3read After the above task is finished use [c]f3read[/c] to read the files from the pen or flash drive f3read /media/flash-drive-mount-point If the out put from f3read shows no corrupted sectors then the USB flash drive is good.

f3probe F3 also comes with a command line utility named f3probe, which is recommended for testing USB flash drives of large capacity due to its fast test speed. As before use [c]lsblk[/c] to see the capacity and the block id for example [c]/dev/sdb[/c] [c]/dev/sdc[/c] [c]/dev/sdd [/c] /dev/sda in most cases will be the linux installation drive sudo f3probe --destructive --time-ops /dev/block-id **Replace block-id with the correct block id The above command will test the drive and return an output showing the actual capacity and and announced capacity.

output when the usb is fake

This is free software; see the source for copying conditions.

WARNING: Probing normally takes from a few seconds to 15 minutes, but
         it can take longer. Please be patient.

Bad news: The device `/dev/sde' is a counterfeit of type limbo

You can "fix" this device using the following command:
f3fix --last-sec=253899 /dev/sde

Device geometry:
	         *Usable* size: 123.97 MB (253900 blocks)
	        Announced size: 125.00 GB (262144000 blocks)
	                Module: 128.00 GB (2^37 Bytes)
	Approximate cache size: 1.00 MB (2048 blocks), need-reset=no
	   Physical block size: 512.00 Byte (2^9 Bytes)

Probe time: 10.33s
 Operation: total time / count = avg time
      Read: 358.0ms / 4275 = 83us
     Write: 9.70s / 31073 = 312us
     Reset: 258.9ms / 1 = 258.9ms