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f3write - test real flash memory capacity

NAME  SYNOPSIS  DESCRIPTION  OPTIONS  EXAMPLE  SEE ALSO  AUTHOR 

NAME

f3write, f3read - test real flash memory capacity

SYNOPSIS

f3write [--start-at=NUM] [--end-at=NUM] <PATH>
f3read
[--start-at=NUM] [--end-at=NUM] <PATH>

DESCRIPTION

F3 (Fight Flash Fraud or Fight Fake Flash) tests the full capacity of a flash card (flash drive, flash disk, pendrive). It writes to the card and then checks if can read it. It will assure you haven’t been sold a card with a smaller capacity than stated.

When writing to flash drive, f3write fills the filesystem with 1GB files named N.h2w, where N is a number (i.e. /[0-9]+/).

WARNING: all data on the tested disk might be lost!

OPTIONS

--start-at=NUM

Initial number of file names. Default value is 1.

--end-at=NUM

Final number of file names. Default value is "infinity".

EXAMPLE

To write over a flash drive mounted at /media/TEST:

$ f3write /media/TEST

To read this flash drive:

$ f3read /media/TEST

SEE ALSO

For detailed information about the F3 tools, see:

https://fight-flash-fraud.readthedocs.io/en/stable/

AUTHOR

F3 was written by Michel Machado <[email protected]>. This manual page was first written by Joao Eriberto Mota Filho <[email protected]>.


Updated 2026-06-01 - jenkler.se | uex.se