Programming on Matus Stafura

My Tips for LeetCode Success: Learning DSA the Right Way

Sat, 15 Nov 2025 10:31:29 +0100

I have solved over 500 problems and this is mostly a personal reminder of tips and thoughts on solving DSA on Leetcode or any other alternative platform.

Main Goal

I am not preparing for any interview and I don’t plan to work for any big tech company. So why am I spending my time solving DSA?

Because I want to be the best I can be.

And If DSA helps me to get closer, then there’s no debate.

How to Automatically Update a Git Repo on Login in Linux

Tue, 16 Sep 2025 00:00:00 +0000

Why would you want to do this?

Yeah, yeah, it happens even to the best of us.

You start committing changes to your repo, and then you forget to push them.

Then you go to another machine, and you realize that your repo is outdated.

BRUH!

To prevent this, you can easily set up a systemd user service that runs a script to git pull your repo every time you log in.

My first homelab

Mon, 20 Jan 2025 00:00:00 +0000

Finally, I found the time to set up my first homelab. To get hands-on experience with advanced Linux topics, virtualization, and Kubernetes, I needed a dedicated server. The truth is, you don’t need anything fancy—an old laptop can work just fine. I opted for a mini version since I might need to carry it to different locations.

Specs

Let me introduce the HP EliteDesk 800 i5-6500T. It’s second-hand but in excellent condition.

How to download torrents with transmission and docker

Mon, 13 Jan 2025 00:00:00 +0000

Since I set up my new homelab, I wanted to separate processes that could run independently on another PC. One of those processes is downloading torrents, which previously required my PC to be running and consumed valuable space.

Requirements

docker installed

Installation

Create a file named docker-compose.yaml and add the following content:

---
services:
  transmission:
    image: lscr.io/linuxserver/transmission:latest
    container_name: transmission
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Etc/UTC
    volumes:
      - ./config:/config
      - ./downloads:/downloads
      - ./watch:/watch
    ports:
      - 9091:9091
      - 51413:51413
      - 51413:51413/udp
    restart: unless-stopped

Running transmission

While in the folder containing the docker-compose.yaml file, start the container. The volumes will be automatically created.

How to install man pages on an ubuntu docker image

Thu, 19 Dec 2024 00:00:00 +0000

As I am preparing for a Linux exam, I need to practice various commands on a separate Docker image and refer to manuals while using it.

By default, Docker images are minimal, and the Ubuntu image does not include man pages.

For instance, when you try to access a manual page, you encounter the following message:

root@54354b49f7a9:/# man man
This system has been minimized by removing packages and content that are
not required on a system that users do not log into.

To restore this content, including manpages, you can run the 'unminimize'
command. You will still need to ensure the 'man-db' package is installed.

To address this, you can use the unminimize command in the Dockerfile to restore the missing components. Here’s how:

How to encrypt and decrypt files with AES-256 with OpenSSL

Thu, 28 Nov 2024 00:00:00 +0000

The worst nightmare is sending and storing sensitive or private data in plain text.

Let’s improve that by encrypting the files with AES-256.

Install OpenSSL

# Let's check if we have OpenSSL installed
openssl version

# If not, let's install openssl
sudo apt update && apt install openssl -y

Encrypt File

# create a file with some content
echo "hello" > test.txt

# Encrypt the file
openssl enc -aes-256-cbc -salt -pbkdf2 -iter 100000 -in test.txt -out example.enc

#### help ################################################################
# -salt     - Ensures that the same plaintext encrypted multiple 
#             times with the same key produces different ciphertexts
# -pbkdf2   - Password-Based Key Derivation Function 2 
#             algorithm used to derive the encryption key from a password
# -iter     - Specifies the number of iterations for the algorithm
##########################################################################

# check if we have encrypted file
ls
# test.txt example.enc

# let's see the contents of encrypted file
cat example.enc
# Salted__�!ei��/�+�΀O��l3%

Yay, no one can read that.