Docker


### Install Docker {#install}
Ubuntu

Install packages to use apt over HTTPS
```bash
sudo apt install apt-transport-https ca-certificates curl software-properties-common
```

Add GPG key for the official Docker repo
```bash
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
```

Add Docker repo to apt
```bash
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
```

Update packages
```bash
sudo apt update
```

Check that Docker installs from the official Docker repo: 
```bash
apt-cache policy docker-ce
```

Install Docker
```bash
sudo apt install docker-ce
```

Verify Docker is installed and running
```bash
sudo systemctl status docker
```

Esp32


### Pinouts {#pinouts}

  - [ESP32 DEVKIT V1 (WROOM)](/images/refs/esp32/esp32.png)
  - [ESP8266 NODE MCU (LOLIN)](/images/refs/esp32/nodemcu.jpeg)
  - [ESP8266 WEMOS D1 MINI](/images/refs/esp32/wemos_d1_mini.png)

### Simple Server {#simple-server}
##### https://hackaday.io/project/186248-esp8266-esp-01-web-server-with-dht11-sensor

Quick WiFi server for ESP32/Arduino

```cpp
#include <ESP8266WiFi.h>

const char* ssid     = "ssid"; // Your ssid
const char* password = "password"; // Your Password
WiFiServer server(80);

void setup() {
  
// Start DHT11  
Serial.begin(115200);
delay(10);
Serial.println();

// Connect to WiFi network
WiFi.mode(WIFI_STA);
Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");

// Start the server
server.begin();
Serial.println("Server started");

// Print the IP address
Serial.println(WiFi.localIP());
}
```


Javascript


## Convert HEX to HSL {#hex-to-hsl}
### Generated by OpenAI text-davinci-003
```js
/** 
* Converts a hex color to its HSL value 
* @param {string} hex - The hex color to be converted 
* @returns {string} - The HSL value of the hex color 
* */

const hexToHSL = (hex) => {
  let result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);

  let r = parseInt(result[1], 16);
  let g = parseInt(result[2], 16);
  let b = parseInt(result[3], 16);

  r /= 255, g /= 255, b /= 255;
  let max = Math.max(r, g, b), min = Math.min(r, g, b);
  let h, s, l = (max + min) / 2;

  if(max == min){
    h = s = 0;  // achromatic
  }else{
    let d = max - min;
    s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
    
    switch(max){
      case r: h = (g - b) / d + (g < b ? 6 : 0); break;
      case g: h = (b - r) / d + 2; break;
      case b: h = (r - g) / d + 4; break;
    }
    h /= 6;
  }

  h = Math.round(h * 360);
  s = Math.round(s * 100);
  l = Math.round(l * 100);

  return `HSL(${h}, ${s}%, ${l}%)`;
}

console.log(hexToHSL("#4BA37B"));  // "HSL(153, 37%, 47%)"
```

This function takes in a hex color as a string argument. It then uses a regular expression to parse the hex color into its individual red, green, and blue components. These are stored as variables and converted to decimal numbers between 0 and 1 by dividing them by 255. The max and min values of the red, green, and blue components are then calculated. 

The hue, saturation, and lightness values are then calculated based on the max and min values. The hue is calculated by determining which of the red, green, and blue components is the max value, and then calculating the difference between that value and the other two components. The saturation and lightness are calculated by determining the difference between the max and min values, and then dividing that by the sum of the max and min values. 

Finally, the hue, saturation, and lightness values are rounded to the nearest integer and the resulting HSL value is returned.

Shell


### ExifTool {#exiftool}
A command-line interface to Image::ExifTool, used for reading and writing meta information in a variety of file types. FILE is one or more source file names, directory names, or "-" for the standard input. Metadata is read from source files and printed in readable form to the console (or written to output text files with -w).

Remove all non-essential data from all photos in a directory

`exiftool -all:all=  ~/Desktop/temp`

Write property to a file

`exiftool -<property>="info" <filename>`

---

### SCP {#scp}
scp copies files between hosts on a network. It uses ssh(1) for data transfer, and uses the same authentication and provides the same security as ssh(1). scp will ask for passwords or passphrases if they are needed for authentication.

Download a file from a remote server

`scp user@192.168.X.XXX:/path/to/remote/file /path/to/local/file`

Download all folders in a directory (recursive)

`scp -r user@192.168.X.XXX:/`

Upload a file to a remote server

`scp /path/to/local/file user@192.168.X.XXX:/path/to/save/on/remote`

Common flags
```bash
-p <port>    Port          // Specify the ssh port
-r           Recursive     // When uploading/downloading an entire directory
-v           Verbose       // Log all the things
```

---

### Snap {#snap}

List installed packages

`sudo snap list`

Install a package

`sudo snap install <package-name>`

Remove a package

`sudo snap remove <package-name>`

---

### tmux {#tmux}
tmux is a terminal multiplexer: it enables a number of terminals to be created, accessed, and controlled from a single screen. tmux may be detached from a screen and continue running in the background, then later reattached.

Start a new session called `001`

`tmux new -s 001`

List all sessions

`tmux ls`

Re-attach a detached session (001)

`tmux attach -t 001`

Common commands
```bash
ctrl+b + %     // split window vertically
ctrl+b + \"     // split window horizontally
ctrl+b + o     // close active pannel
```

### IP Tools {#ip-tools}

__General__

Get local IP


`ip a | grep 192.168`

__Dig__

Install Dig

_Ubuntu_

`sudo apt-get install dnstools`

_Arch/Manjaro_

`sudo pacman -S dnsutils`

Get public IP address

`dig +short myip.opendns.com @resolver1.opendns.com`

Ubuntu


### show package version history {#package-version-history}

```bash
sudo apt-cache showpkg firefox 01
```

### downgrade a package {#downgrade-package}

```bash
apt-get install --reinstall --allow-downgrades <package-name>=<version> -y
```

### lock package version {#lock-package-version}
```bash
apt-mark hold <package-name>
```

### Change password {#change-password}
```bash
passwd
```

### initial server setup {#initial-setup}

More often than not I'm starting from the Ubuntu container template (CT) in Proxmox, so the following commands are assuming you're logged in as `root`. When starting from the Ubuntu ISO, the current user/password will probably be `ubuntu`. Either add `sudo` to the following commands or log in as root if that's the case.

Update packages
```bash
apt update && apt upgrade
```

Add new user
```bash
adduser <username>
```

Give new user privs.
```bash
usermod -aG sudo <username>
```

Logout and login as new user. (`sudo` will be required after this step)
```bash
logout
```

Remove the shell from root
```bash
sudo usermod -s /usr/sbin/nologin root
```

Disable root from logging in
```bash
sudo usermod -L root
```

Remove default `ubuntu` user (only if using the full Ubuntu ISO)
```bash
sudo userdel ubuntu
```

Set up UFW rules
```bash
sudo ufw default deny incoming
```
```bash
sudo ufw enable
```

Install ZSH
```bash
sudo apt install zsh
```

Set ZSH as default shell and logout/login
```bash
sudo chsh -s $(which zsh)
```
```bash
logout
```

Install Oh My ZSH
```bash
sh -c "$(wget https://raw.github.com/ohmyzsh/ohmyzsh/master/tools/install.sh -O -)"
```

Change ZSH theme (I like `cloud` the best 🤷‍♀️)
```bash
sudo nano ~/.zshrc
```

Install tmux
```bash
sudo apt install tmux
```

Privacy, Linux, home automation and gardening are my main interests these days. I really just needed a place to put some things, so here we are.