sudo arp-scan --localnet Gives a list of connected devices, with IP and MAC and manufacturer name when recognised. sudo nmap -sn x.x.x.x Attempts to resolve hostnames.

1. Generate a key on the client

ssh-keygen -t ed25519 -C "client name" Keep the default file name when prompted. Choose a passphrase and finish. Now the key is stored in ~/.ssh/id_ed25519.pub

2. Copy the public key to the server

ssh-copy-id -i ~/.ssh/id_ed25519.pub user@x.x.x.x This will add the public key to the server, stored in ~/.ssh/authorized_keys

3. Simplify the connection

It is possible to add host information in one config file: ~/.ssh/config Add for every host: Host servername Hostname x.x.x.x User user IdentityFile ~/.ssh7id_ed25519 IdentitiesOnly yes

4. Now it is possible to connect with:

ssh servername A passphrase will be required if set.

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How to use SSH Key

To create a list of servers with easy access, create or edit

Host dev-box
    HostName 192.168.1.50
    User admin
    Port 22 

To connect: Just type go ssh dev-box

To create and use an SSH Key

Generate your key: go ssh-keygen Copy the key to your server (you'll type the password one last time here): go ssh-copy-id dev-box

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How to fix broken WiFi after a kernel update on MacBook Pro late 2012

Install the proprietary Broadcom STA driver

sudo apt update
sudo apt install broadcom-sta-dkms

Confirm the correct kernel headers and build tools

sudo apt install linux-headers-$(uname -r) build-essential dkms

Force a DKMS rebuild in case the kernel upgrade broke it

sudo dkms autoinstall

Load the correct driver

sudo modprobe wl

Check:

lsmod | grep wl
lsmod | grep -E 'wl|brcm|bcma'
dmesg | grep -i wl

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Working with GitHub from Linux CLI

This guide shows how to create and manage a GitHub repository entirely from the Linux command line.

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1. Setup Git

sudo apt update
sudo apt install git

Configure your identity (used for commits):

git config --global user.name "Your Name"
git config --global user.email "your.email@example.com"

Check configuration:

git config --list

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2. Generate SSH Key (optional but recommended)

ssh-keygen -t ed25519 -C "your.email@example.com"

Copy the public key:

cat ~/.ssh/id_ed25519.pub

Add it to GitHub under Settings → SSH and GPG keys → New SSH key.

Test connection:

ssh -T git@github.com

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3. Create a Local Repository

mkdir my-project
cd my-project
git init

This creates a new Git repository in the folder.

Add a file and commit it:

echo "# My Project" > README.md
git add README.md
git commit -m "Initial commit"

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4. Create a GitHub Repository from CLI

Using HTTPS (if SSH not configured)

Go to https://github.com/new and create an empty repository manually.

Then connect it:

git remote add origin https://github.com/username/my-project.git

Using SSH (preferred)

git remote add origin git@github.com:username/my-project.git

Push the local repo to GitHub:

git branch -M main
git push -u origin main

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5. Making Changes and Updating the Repository

Edit files as needed, then:

git status
git add .
git commit -m "Describe changes"
git push

To pull updates from GitHub:

git pull

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6. Cloning Existing Repositories

git clone https://github.com/username/repository.git
# or
git clone git@github.com:username/repository.git

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7. Branching

Create and switch to a new branch:

git checkout -b feature-branch

Push a new branch to GitHub:

git push -u origin feature-branch

Merge back to main:

git checkout main
git merge feature-branch
git push

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Summary

• git init → Create a repo
  
• git add / commit → Stage and save changes
  
• git remote add origin → Link to GitHub
  
• git push / pull → Sync changes
  
• git branch / merge → Manage versions

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World population from 10.000 BCE to now

One of the most amazing datasets

from ourworldindata.org

When I was born in 1966, the world population was 3.4 billion; now it is more than double that.

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Coding Microbit in C++ with Debian 12

First, we need to set the environment: 1. Installing Yotta and '''srecord''' (this is needed to create .hex)

sudo apt install yotta srecord

1. Clone example git clone https://github.com/lancaster-university/microbit-samples cd microbit-samples
2. Setup the target for building yotta target bbc-microbit-classic-gcc-nosd@https://github.com/lancaster-university/yotta-target-bbc-microbit-classic-gcc
3. Build example yotta build 5.Copy .hex to Microbit folder cp ./build/bbc-microbit-classic-gcc/source/microbit-samples-combined.hex /media/"user"/MICROBIT

Reference: Reference

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