---
name: "f3read"
section: "1"
platform: "linux"
package: "f3"
version: "9.0-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/f3read"
---

# f3read(1)

test real flash memory capacity

## 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 \<michel@digirati.com.br\>. This manual page was first written by Joao Eriberto Mota Filho \<eriberto@eriberto.pro.br\>.