
Hi everyone, this is a quick post just to open this section on my website where I'll share some things I learned along the way.

Lately, I've been looking for flash cards for two of my consoles, a Nintendo Switch and a R365 (a portable emulation console) and as I was noticing that the prices vary significantly across marketplaces, I decided to investigate a little further and see how I can check if the card I bought was indeed delivering what was promised and that it wasn't counterfeit.

That's why I found F3 - Fight Flash Fraud (or Fight Fake Flash). According to [their website](https://fight-flash-fraud.readthedocs.io/en/latest/introduction.html):

> f3 is a simple tool that tests flash cards capacity and performance to see if they live up to claimed specifications. It fills the device with pseudorandom data and then checks if it returns the same on reading.

I'll give a little example of how I run this on my macOS, but they have instructions for [Linux](https://fight-flash-fraud.readthedocs.io/en/latest/introduction.html#compile-stable-software-on-linux-or-freebsd) and [Windows](https://fight-flash-fraud.readthedocs.io/en/latest/introduction.html#compile-stable-software-on-windows-cygwin).

## Installing F3

First, to install using [Homebrew](https://formulae.brew.sh), run the following in your terminal:

```
brew install f3
```

## Finding the mount point

With F3 installed, you need to find the mount point for the device you want to verify. Run `df` in the terminal, and it'll give you an output similar to this one

```
╰─ df
Filesystem     512-blocks      Used Available Capacity iused     ifree %iused  Mounted on
... (Other devices)
/dev/disk2s1     10485672   4092464   6352200    40%      61  31761000    0%   /System/Volumes/Update/SFR/mnt1
/dev/disk3s1    965595304  34732424 193350936    16%  453127 966754680    0%   /System/Volumes/Update/mnt1
/dev/disk4s1    124702976      8192 124694784     1%       0         0     -   /Volumes/MY_SD_CARD
```

In the last line, `MY_SD_CARD` is my SD card label (the same label that appears in Finder/Explorer). Copy the value in the `Mounted On` column and use it as a parameter for F3.

## Running the test

We'll use two programs in order to write large files to the disk and read them after to check if the flash card contains exactly the written files.

```
╰─ f3write /Volumes/MY_SD_CARD
╰─ f3read /Volumes/MY_SD_CARD
```

At the end of each command, you'll receive some useful information such as:

```
(At the end of f3write)
Free space: 0.00 Byte
Average Writing speed: 4.90 MB/s

(At the end of f3read)
  Data OK: 29.71 GB (62309312 sectors)
Data LOST: 0.00 Byte (0 sectors)
           Corrupted: 0.00 Byte (0 sectors)
    Slightly changed: 0.00 Byte (0 sectors)
         Overwritten: 0.00 Byte (0 sectors)
Average Reading speed: 9.42 MB/s
```

This is a case where the card is operating correctly and is living up to its expected specifications. You can find other useful resources about this tool [on their website](https://fight-flash-fraud.readthedocs.io/en/latest/usage.html).

Thanks for reading this! I decided to write because this is a very common topic for gamers or electronics enthusiasts, since we use those types of cards every day in consoles, cameras and other day-to-day devices. I'll not recommend any reliable store to buy those cards, but pay attention on the price, especially in marketplaces like Amazon, eBay or MercadoLivre (for South Americans) and try to buy directly from the manufacturer’s store if possible.


Checking if the card you bought was indeed delivering what was promised and that it wasn't counterfeit

How to recognize poor quality Flash Memory Cards with F3


> 💡 **tl/dr**; You can set up a new system using **dotfiles** and an installation script in minutes. This post tries to explains some things about dotfiles and we will build a repository together

**Dotfiles** are configuration files typically stored in a user's home directory (the directory represented by the symbol `~` on Unix-based operating systems) and that begin with a dot (`.`) in their file name.

These files are used to **store** settings for the various programs and tools that a user can use on their system. Files like `.bashrc`, `.zshrc`, `.vimrc` and `.gitconfig` are examples (just to name a few) that practically every user has on their machine.

Make a test on your machine and run the following command to view just some of the dotfiles that are in your user directory.

```bash
find ~ -type f -iname ".*" -maxdepth 1
```

For example, the file `.bashrc` is a configuration file for the **[Bash](https://www.gnu.org/software/bash/)** shell (a popular command-line interface for systems Unix-like). It can contain settings such as the **prompt displayed** when the shell is opened, **aliases** (or shortcuts) for frequently used commands, and custom functions. Another example is the `.vimrc` file is a configuration file for the **Vim** text editor and can contain settings such as the color scheme to use, the line format and custom keyboard shortcuts.

In this post, we will talk a little about how to start your dotfiles versioning, what to version, good practices, security issues and I will share with you my own version of **dotfiles**

## Why is this important?

Many users choose to manage their **dotfiles** using version control systems such as **Git** so that they can track changes to their configurations over time and easily synchronize their configurations when starting a new development environment on a new machine.

Imagine that your development machine, whether used for studies or work, has a problem that prevents you from continuing to use the system. Regardless of the reason, “fixing” this problem usually involves a new OS installation and all the work of reconfiguring a development environment from scratch. This new installation will certainly have a multitude of details that you usually configure little by little, over time, things like **color of your terminal**, **font of your text editor**, etc.

The objective of versioning your **dotfiles** is to save time with this process and maintain a development environment with your changes over time, being able to return to old configurations if something goes wrong during a change or there is simply a need to reconfigure the environment on a clean install of your OS.


Hi! I'm
Diogo Moreira

Latest updates

2026

How to recognize poor quality Flash Memory Cards with F3

2023

Versioning .dotfiles

Hi! I'm Diogo Moreira

Latest updates

2026

How to recognize poor quality Flash Memory Cards with F3

2023

Versioning .dotfiles

Hi! I'm
Diogo Moreira