Lybekk

Lybekk https://lybekk.tech Personal/Portfolio site. Zola en Tue, 07 Jul 2026 00:00:00 +0000 UUID Generator Tue, 07 Jul 2026 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/uuid-generator/ https://lybekk.tech/uuid-generator/ <p>Generate random version 4 (random) UUIDs. Everything runs in your browser using the Web Crypto API. Nothing is sent anywhere.</p> <section class="tool" id="uuid-tool"> <p><label>How many (1–100)<br><input type="number" id="uuid-count" min="1" max="100" value="5" inputmode="numeric"></label></p> <p><button type="button" id="uuid-generate">Generate</button><button type="button" id="uuid-copy">Copy</button></p> <p><textarea id="uuid-output" rows="6" readonly aria-label="Generated UUIDs"></textarea></p> <p id="uuid-status" role="status" aria-live="polite"></p> </section> <script src="/uuid-generator.js" defer></script> Termux: Install Google Cloud CLI Sat, 16 Jan 2021 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/guide/termux-install-google-cloud-cli/ https://lybekk.tech/guide/termux-install-google-cloud-cli/ <blockquote> <p>These instructions specifically targets the following error during installation: <samp class="error" style="display: inline-block;">ERROR: (gcloud.components.update) The following components are unknown [anthoscli, kuberun].</samp></p> </blockquote> <ol> <li>First: Run <ul> <li><code>curl https://sdk.cloud.google.com | bash</code></li> <li><em>Note: This will fail when trying to install components. Ignore this.</em></li> </ul> </li> <li>Then <code>~/google-cloud-sdk/install.sh --override-components</code> <ul> <li>(without specifying components)</li> <li>Will add gcloud to $PATH</li> </ul> </li> <li>And then <code>gcloud components install gsutil</code></li> <li>Finally <code>gcloud init</code></li> </ol> <p>Google cloud's shell can finally be accessed with <code>gcloud cloud-shell ssh</code></p> MySQL Sun, 20 Dec 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/mysql/ https://lybekk.tech/cheatsheet/mysql/ <h2 id="linux-stop-mysql-server-from-running-at-boot">(Linux) Stop MySQL Server from running at boot</h2> <pre><code data-lang="bash">sudo systemctl disable mysql </code></pre> React cheatsheet Tue, 27 Oct 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/react/ https://lybekk.tech/cheatsheet/react/ <h2 id="run-function-on-component-render">Run function on component render</h2> <pre><code data-lang="javascript">import React, { useEffect } from "react" useEffect(() => { console.log('This runs on every render') }) // add and empty array as a callback to run once, instead of on every render useEffect(() => { console.log('This runs exactly once') }, []) </code></pre> Dart cheatsheet Sun, 25 Oct 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/dart/ https://lybekk.tech/cheatsheet/dart/ <h2 id="useful-libraries">Useful libraries</h2> <h3 id="standard-library">Standard library</h3> <ul> <li>dart:async - Enables async/await functions</li> <li>dart:io - For read/write operations on the local filesystem <ul> <li>https://api.dart.dev/stable/2.10.2/dart-io/Directory-class.html</li> </ul> </li> <li>dart:convert - Used for, among other things, JSON encoding and decoding</li> </ul> <h2 id="print">Print</h2> <p>print('Hello, World!');</p> <h2 id="basic-function">Basic function</h2> <p>void main() { print('Hello, World!'); }</p> <h2 id="run-dart-script-from-the-command-line">Run Dart script from the command line</h2> <p><code>dart /path/to/script.dart</code></p> <h2 id="directory">Directory</h2> <p>var myDir = new Directory('/home/user/dir/');</p> <h3 id="list-files-in-a-directory">List files in a directory</h3> <pre><code data-lang="dart">var myDir = new Directory('/home/user/dir/'); void checkDir(theDir) { theDir.exists().then((isThere) { isThere ? print('exists') : print('non-existent'); listDir(theDir); }); } void listDir(theDir) { theDir.list(recursive: true, followLinks: false) .listen((FileSystemEntity entity) { print(entity.path); }); } checkDir(myDir); </code></pre> <h2 id="handy-resources-from-around-the-web">Handy resources from around the web</h2> <ul> <li><a rel="external" href="https://codingwithjoe.com/dart-fundamentals-working-with-json-in-dart-and-flutter/">Working with JSON</a></li> <li><a rel="external" href="https://flutter.dev/docs/development/data-and-backend/json#manual-encoding">JSON and serialization </a></li> <li><a rel="external" href="https://flutter.dev/docs/cookbook/persistence/reading-writing-files">Reading and writing files</a></li> </ul> PowerShell Wed, 14 Oct 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/powershell/ https://lybekk.tech/cheatsheet/powershell/ <h2 id="find-content-in-files">Find content in files</h2> <p><code>Get-Content .\file.txt | Select-String 'String To Find'</code></p> Regex Wed, 14 Oct 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/regex/ https://lybekk.tech/cheatsheet/regex/ <h2 id="use-in-text-editors">Use in text editors</h2> <p>Regular expressions can be used for lookups on text editors.</p> <p>Find and highlight the entire line</p> <blockquote> <p><code>.*something.*</code> Works in KWrite, Kate, Notepad++, Atom, and more.</p> </blockquote> Windows CMD Wed, 14 Oct 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/windows-cmd/ https://lybekk.tech/cheatsheet/windows-cmd/ <h2 id="findstr">FINDSTR</h2> <p>GREP equivalent for Windows CMD.</p> <blockquote> <p>Syntax: <code>findstr pattern filename</code></p> </blockquote> <p>To search for a string in all the files in the current directory: <code>findstr /I "text to find" *</code></p> How to: Rip audio from YouTube with Python Wed, 14 Oct 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/guide/rip-audio-from-youtube-with-python/ https://lybekk.tech/guide/rip-audio-from-youtube-with-python/ <blockquote> <p><em><strong>Disclaimer</strong></em></p> <p><em>Ripping audio from copyrighted music videos is, in most cases, not legal.</em></p> </blockquote> <h2 id="prerequites">Prerequites</h2> <p><code>pip3 install youtube_dl</code></p> <h2 id="script">Script</h2> <p>Save this to a file and run it with a python interpreter. (<code>python3 this_script.py</code>)</p> <pre><code data-lang="python">import youtube_dl from pathlib import Path options = { 'format': 'bestaudio/best', 'extractaudio' : True, # only keep the audio 'audioformat' : "mp3", # convert to mp3 'noplaylist' : True, # only download single song, not playlist } options["artist"] = input("Artist:") options["track"] = input("Track:") options["genre"] = input("Genre:") print("Youtube video URL:") url = input() filename = f'{options["artist"]} - {options["track"]}.mp3' h = Path.home() f = 'Downloads' path = h.joinpath(f) if not path.exists(): path = h.joinpath(f.lower()) path = path.joinpath(filename) options["outtmpl"] = str(path) with youtube_dl.YoutubeDL(options) as ydl: ydl.download([url]) </code></pre> CouchDB cheatsheet Sat, 19 Sep 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/couchdb/ https://lybekk.tech/cheatsheet/couchdb/ <blockquote> <p><strong>Assumptions for this article</strong></p> <p>Server is available locally on <code>http://localhost:5984/</code></p> <p>Database name is <code>mydb</code></p> </blockquote> <h2 id="fetch-all-documents-using-curl">Fetch all documents using CURL</h2> <p>syntax/structure http://localhost:5984/mydb/_all_docs?include_docs=true</p> <p>Example</p> <pre><code data-lang="bash">curl -X GET http://localhost:5984/mydb/_all_docs?include_docs=true # If authentication is required curl -X GET http://admin:password@localhost:5984/mydb/_all_docs?include_docs=true </code></pre> KDE Thu, 10 Sep 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/kde/ https://lybekk.tech/cheatsheet/kde/ <h2 id="performance-tips">Performance tips</h2> <h3 id="disable-baloo-file-indexer">Disable Baloo File Indexer</h3> <p>Navigate to <code>System settings -> Search -> File Search</code>. Untick <strong>"Enable file search"</strong> to stop Baloo from spending system resources on continuous file indexing. Especially useful if you're low on RAM/memory.</p> Linux cheatsheet Mon, 07 Sep 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/linux/ https://lybekk.tech/cheatsheet/linux/ <h2 id="split-cut-extract-clip-from-a-video-file">Split/cut/extract clip from a video file</h2> <pre><code data-lang="bash">ffmpeg -ss 00:00:46 -t 00:00:30 -i input_file.mp4 -vcodec copy -acodec copy output_file.mp4 </code></pre> <pre><code>Command explanation: ffmpeg -ss <start-time> -t <target clip duration> -i <input_file.mp4> -vcodec copy -acodec copy <output_file.mp4> </code></pre> Kotlin cheatsheet Sat, 22 Aug 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/kotlin/ https://lybekk.tech/cheatsheet/kotlin/ <h2 id="create-a-function">Create a function</h2> <pre><code data-lang="kotlin">fun main() { // 2 println("Hello, World!") // 3 } </code></pre> <h2 id="print-to-console">Print to console</h2> <pre><code data-lang="kotlin">// Print with newline, I.E. move cursor to new line. println("Hello Werldz!") // Print without adding newline print("Enter text: ") </code></pre> <h2 id="prompt-for-input-and-print-to-console">Prompt for input and print to console</h2> <pre><code data-lang="kotlin">print("Enter text: ") val stringInput = readLine()!! println("You entered: $stringInput") </code></pre> SSH cheatsheet Wed, 29 Jul 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/ssh/ https://lybekk.tech/cheatsheet/ssh/ <p><em>SSH - Secure Shell</em></p> <h2 id="forward-a-port-from-a-remote-source-i-e-a-vps-to-specific-port-on-localhost">Forward a port from a remote source (I.E. a VPS) to specific port on localhost</h2> <pre><code data-lang="bash">ssh -L 65432:localhost:80 user@111.222.333.444 -p 54321 -i .ssh/id_rsa_selected_key </code></pre> <p><em>Command breakdown</em> <code>ssh</code> No explanation needed (?)</p> <p><code>-L 65432:localhost:80</code> The forwarding part of the command. 65432 is the port you want to forward to on the target/receiver/local device. localhost:80 is the port om the remote.</p> <p><code>user@111.222.333.444 -p 54321</code> The remote's user, IP-address and SSH port (if port is not specifiec in remote's settings, defaults to 22)</p> <p><code>-i .ssh/id_rsa_selected_key</code> '-i' is used when a specific SSH key is needed</p> <h2 id="creating-a-key">Creating a key</h2> <pre><code data-lang="bash">ssh-keygen -t rsa -C "some.identifier@name.com" </code></pre> How to: Get Netlify Bandwith Usage Programatically For Free Mon, 27 Jul 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/guide/get-netlify-bandwidth-usage/ https://lybekk.tech/guide/get-netlify-bandwidth-usage/ <p>Netlify's Analytics feature, at the time of writing, costs 9$. This may be a bit steep if all you need is to measure your site's traffic. This is an attempt on a livable compromise.</p> <h2 id="using-python">Using Python</h2> <h3 id="explanation">Explanation</h3> <p><em>In the script below, replace the following variable's values</em></p> <dl> <dt style="font-weight: bold;">ACCOUNT_NAME</dt> <dd>The account name associated with the account.</dd> <dt style="font-weight: bold;">SITE_NAME</dt> <dd>The site name can be found in 'Site information' in the project's settings, or at the top in the overview.</dd> <dt style="font-weight: bold;">EMAIL</dt> <dd>The email used during account registration.</dd> <dt style="font-weight: bold;">PERSONAL_ACCESS_TOKEN</dt> <dd>Created at https://app.netlify.com/user/applications</dd> </dl> <h3 id="full-python-script">Full Python script</h3> <pre><code data-lang="python">import requests # Edit these ACCOUNT_NAME = 'youraccountname' SITE_NAME = 'projectsitename' EMAIL = 'name@example.com' PERSONAL_ACCESS_TOKEN = "<your Netlify personal access token>" # Leave the rest bandwidth_api_url = 'https://api.netlify.com/api/v1/accounts/{}/bandwidth'.format(ACCOUNT_NAME) auth_string = "Bearer " + PERSONAL_ACCESS_TOKEN response = requests.get(bandwidth_api_url, headers = { 'User-Agent': '{0} ({1})'.format(SITE_NAME, EMAIL), "Authorization": auth_string }) response = response.json() # Optional printing to console. Can be removed print('Raw response: ', response) def calculate(key): return int(response[key]) / 1000000 print_list = { "Included in plan": calculate("included"), "Used": calculate("used"), "Remaining": calculate("included") - calculate("used"), } print('Human readable:') for item in print_list.items(): print(item[0], ': ', round(item[1], 2), ' MB') </code></pre> <p><em>Note: The returned usage will be a bit higher than how Netlify calculates it.</em></p> <h2 id="netlify-bandwidth-checker-tool">Netlify Bandwidth Checker Tool</h2> <p>If you are comfortable pasting your <strong>Personal Access Token</strong> in a web form, try this tool, which does the same as the Python script, only in JavaScript. One way to mitigate risk is to create a token, and revoke it just after using this tool.</p> <p><em>Note: The script is executed client-side. No information is exchanged with lybekk.tech</em></p> <section class="tool" id="netlify-bandwidth"> <form id="netlify-bandwidth-form"> <p><label>Personal access token<br><input type="password" name="pat" autocomplete="off"></label></p> <p><label>Site name<br><input type="text" name="siteName" autocomplete="off"></label></p> <p><label>Account name<br><input type="text" name="accName" autocomplete="off"></label></p> <p><label>Account email<br><input type="text" name="accEmail" autocomplete="off"></label></p> <p><button type="submit">Get</button></p> </form> <p><label><input type="checkbox" id="netlify-save"> Save credentials for next time</label></p> <p><small>* Uses localStorage in your browser. Credentials are never sent to lybekk.tech.</small></p> <table id="netlify-bandwidth-results"></table> </section> <script src="/netlify-bandwidth.js" defer></script> How To: Use Fluent UI Icons in Gatsby Sun, 26 Jul 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/guide/use-fluentui-icons-in-gatsby/ https://lybekk.tech/guide/use-fluentui-icons-in-gatsby/ <h2 id="prerequisites">Prerequisites</h2> <ul> <li>A running Gatsby development environment with Fluent UI</li> </ul> <h2 id="first-initialize-icons">First - Initialize icons</h2> <p>Fluent UI React's official documentation instructs you to include the below lines in the root entry file.</p> <pre><code data-lang="javascript">import { initializeIcons } from '@uifabric/icons'; initializeIcons(); </code></pre> <p>In <strong>Gatsby</strong>, an easier and more straightforward way is to include these lines in <code>index.js</code> or a layout component (I.E. <code>Layout.js</code>).</p> <blockquote> <p>Another possible solution may be to put them in one of Gatsby's API files.</p> </blockquote> <p>By default, when a user visits the deployed Gatsby app, all icons will be downloaded from one of Microsoft servers.</p> <p>To <strong>avoid</strong> this behaviour, do a couple of small adjustments.</p> <ol> <li>Copy the icons from <code>your_project\node_modules\@uifabric\icons\fonts</code> to a subdirectory in your projects 'static' folder.</li> <li>Modify the lines from earlier slightly, as below, where the parameter for <code>initializeIcons()</code> is the path to where the icons are.</li> </ol> <pre><code data-lang="javascript">import { initializeIcons } from '@uifabric/icons'; initializeIcons('https://lybekk.tech/fluenticons/'); </code></pre> <p><em>The slash '/' at the end is important</em></p> <p>Now Gatsby will load the icons with the same performance and guarantees as the other files, ensuring correct rendering.</p> <blockquote> <p>See an example of Fluent UI running on Gatsby here: <a rel="external" href="https://lybekk.tech/tools/uuidgenerator/">Lybekk Tech - UUID Generator</a></p> </blockquote> <hr /> <p>Further documentation on using <a rel="external" href="https://github.com/microsoft/fluentui/wiki/using-icons">icons with Microsoft's Fluent UI</a></p> <p><em>As an added bonus, a way to use Font Awesome instead of Fluent UI icons.</em></p> <pre><code data-lang="javascript">import { registerIcons } from '@uifabric/styling'; import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'; import { faCode } from '@fortawesome/free-solid-svg-icons'; registerIcons({ icons: { Filter: <FontAwesomeIcon icon={faCode} /> } }); </code></pre> Run a simple Python CGI on Apache Web Server Mon, 20 Jul 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/guide/python-cgi-on-apache-web-server/ https://lybekk.tech/guide/python-cgi-on-apache-web-server/ <h2 id="prerequisites">Prerequisites</h2> <ul> <li>Python 3.x</li> </ul> <h2 id="first-things-first">First things first</h2> <p>First, save the script below to a file.</p> <pre><code data-lang="python">#!/usr/bin/env python3 import cgi from string import Template # enable debugging import cgitb cgitb.enable() print('Content-Type: text/html; charset=utf-8\n') </code></pre> <h2 id="then">Then</h2> <ol> <li>Configure Apache's configuration file <ol> <li>Open the config file in any editor. Usually exists in <code>/etc/apache2/apache2.conf</code>. Example: <code>sudo nano /etc/apache2/apache2.conf</code></li> <li>Put this in at the end: <code>ScriptAlias /myscript/ "/var/www/html/cgi-bin/your_script.py"</code>. 'myscript' is the URL you want the script at.</li> </ol> </li> <li>Put the Python script in cgi-bin (usually <code>/var/www/html/cgi-bin/</code>) <ol> <li>Example: <code>sudo cp /path/to/script/your_script.py /var/www/html/cgi-bin/your_script.py</code></li> </ol> </li> <li>Make sure Apache has permission to execute the file <code>chmod +x your_script.py</code></li> </ol> CSS cheatsheet Mon, 13 Jul 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/css/ https://lybekk.tech/cheatsheet/css/ <h2 id="centering-items">Centering items</h2> <p>Easily center items both horizontally and vertically.</p> <pre><code data-lang="css">div { display: grid; place-items: center; } </code></pre> Git cheatsheet Mon, 13 Jul 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/git/ https://lybekk.tech/cheatsheet/git/ <h2 id="commands">Commands</h2> <table><thead><tr><th>Command</th><th>Description</th></tr></thead><tbody> <tr><td><code>git init</code></td><td>Initializes/creates a new repository</td></tr> <tr><td><code>git clone</code></td><td>Clone a repository into current working directory</td></tr> <tr><td><code>git status</code></td><td>View changes since last commit</td></tr> <tr><td><code>git status -u</code></td><td>View untracked files, expanding subdirectories</td></tr> <tr><td><code>git add <filename></code></td><td>Add file to commit</td></tr> <tr><td><code>git commit -m "message describing commit"</code></td><td>Skip editor, directly adding commit message</td></tr> <tr><td><code>git commit -a</code></td><td>Commit all edits</td></tr> <tr><td><code>git push origin master</code></td><td>send master branch to remote repository</td></tr> <tr><td><code>git pull</code></td><td>Update local repository with master branch</td></tr> </tbody></table> JavaScript cheatsheet Mon, 13 Jul 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/javascript/ https://lybekk.tech/cheatsheet/javascript/ <h2 id="generate-uuid-v4">Generate UUID (v4)</h2> <pre><code data-lang="javascript">function uuidv4() { return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(/[xy]/g, function(c) { var r = Math.random() * 16 | 0, v = c == "x" ? r : (r & 0x3 | 0x8); return v.toString(16); }); } </code></pre> <h2 id="styling">Styling</h2> <pre><code data-lang="javascript">let element = document.querySelector("#navbar-foo"); /* Remove or add a CSS class depending on if it exists or not */ element.classList.toggle("is-active"); /* Add multiple CSS classes in one go */ element.classList.add("navbar-item", "is-capitalized"); /* Style the HTML element directly */ element.style.display = "block"; /* Set multiple Style Object Properties Using the generic setAttribute method */ element.setAttribute("style", "position: fixed; bottom: 0; width: 50vw; left: 25%;"); </code></pre> <h2 id="send-and-retrieve-data-using-fetch-api">Send and retrieve data using Fetch API</h2> <p><em>All examples demonstrates Async fetch. Fetch API is also available using promises</em></p> <p><strong>(PUT) Update a JSON resource at an endpoint</strong></p> <pre><code data-lang="javascript">async function update_document(doc) { const url = 'https://example.com/json_endpoint'; try { const response = await fetch(url, { method: "PUT", body: JSON.stringify(doc), headers: { "Content-Type": "application/json" } }); const result = await response.json(); return await result; } catch (error) { console.log(error); } } const doc = { foo: "bar", test: true }; update_document(doc); </code></pre> <h2 id="create-html-elements">Create HTML elements</h2> <pre><code data-lang="javascript">const list = document.querySelector("#list"); let element = document.createElement("LI"); /* add another element inside the list item */ let link = document.createElement("A"); link.textContent = "Visit site"; link.href = "https://lybekk.tech"; element.appendChild(link); list.appendChild(element); </code></pre> <h2 id="create-an-onclick-event-on-an-html-element">Create an onclick event on an HTML element</h2> <pre><code data-lang="javascript">const btn = document.getElementById("button"); btn.onclick = function() { const popup = document.getElementById("popup"); popup.style.display = "none"; }; </code></pre> <h2 id="accessing-in-browser-storage">Accessing in-browser storage</h2> <p>Interface with the Web Storage API</p> <h3 id="local-storage">Local Storage</h3> <pre><code data-lang="javascript">/* Retrieve an item */ localStorage.getItem('weather'); /* Save a string*/ localStorage.setItem('weather', 'Snow'); /* Save an object */ localStorage.setItem( 'weather', JSON.stringify({ hour: 08, type: 'Hail' }) ); </code></pre> <h3 id="session-storage">Session Storage</h3> <p>Session storage interaction works in the same way as Local Storage. Just replace <code>localStorage</code> with <code>sessionStorage</code></p> <h2 id="pick-random-item-from-an-array">Pick random item from an array</h2> <pre><code data-lang="javascript">const items = ["Item one", "Another item", "Item, the third"] function item() { const item = items[Math.floor(Math.random() * items.length)]; return item } console.log(item()) </code></pre> <h2 id="includes">includes()</h2> <h3 id="strings">Strings</h3> <pre><code data-lang="javascript">const str = "Hello world, welcome to the universe."; const n = str.includes("world"); </code></pre> <h3 id="array">Array</h3> <pre><code data-lang="javascript">const numbers = [10, 12, 1, 2, 0] if (numbers.includes(1) { console.log("Exists") } </code></pre> <h2 id="some">some()</h2> <pre><code data-lang="javascript">const numbers = [10, 12, 1, 2, 0] const isTrue = numbers.some(number => { return number > 2 }) if (isTrue) { console.log("This is true") } </code></pre> Python cheatsheet Thu, 09 Jul 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/python/ https://lybekk.tech/cheatsheet/python/ <h2 id="generic">Generic</h2> <p><strong>Retrieve device hostname</strong></p> <pre><code data-lang="python">import socket HOSTNAME = socket.gethostname() print(HOSTNAME) </code></pre> <p><strong>Get help for a Class object</strong></p> <pre><code data-lang="python">help(TheClassObject) </code></pre> <p><strong>Parse & Dump a JSON file</strong></p> <pre><code data-lang="python">import json with open('/path/to/file.json', "r") as f: file_contents = json.loads( f.read() ) print( json.dumps(file_contents, indent=4) ) </code></pre> <p><strong>Write to file</strong></p> <pre><code data-lang="python">with open('/path/to/file.txt', "w") as f: f.write( "A string, dumped JSON or the like" ) </code></pre> <p><strong>Get environment variable</strong></p> <pre><code data-lang="python">import os variable = os.environ['some_variable_name'] </code></pre> <p><strong>Execute a shell script</strong></p> <pre><code data-lang="python">import subprocess subprocess.Popen("script2.sh", shell=True) #Note: *<code>os.system("script2.sh")</code> is not recommended* </code></pre> <h2 id="collection-types">Collection types</h2> <pre><code data-lang="python">my_list = ["an item", "another item", "A third item. Can you believe it?"] my_tuple = ("this", "will be", "unchangeable") my_set = {"the order", "of these", "are not guaranteed"} my_dictionary = { "key1": "Value 1", "Key 2": 42 } </code></pre> <blockquote> <p><em>Lists and Tuples are 'ordered'. Items will appear as they are inserted</em></p> <p><em>Sets and Dictionaries are not ordered collection types</em></p> </blockquote> <h2 id="run-another-python-script">Run another Python script</h2> <p>Runs another Python script in the same process as the script executing the command</p> <pre><code data-lang="python">exec(open("script2.py").read()) </code></pre> <h2 id="dict-comprehension">Dict comprehension</h2> <pre><code data-lang="python">[print(key, value) for key, value in some_dictionary.items()] </code></pre> <h2 id="quick-http-server">Quick HTTP server</h2> <p>Establish a provisionary web server</p> <pre><code data-lang="python">python -m http.server # for Python 3 </code></pre> <h2 id="quick-http-server-script">Quick HTTP server (Script)</h2> <pre><code data-lang="python">import http.server import socketserver import cgi import webbrowser PORT = 8787 # Binds to localhost only. "" for exposing this to network interfaces HOST = "localhost" # Launches the default web browser Opens the directory url = 'http://' + HOST + ":" + str(PORT) webbrowser.open_new_tab(url) # Magic Handler = http.server.SimpleHTTPRequestHandler with socketserver.TCPServer((HOST, PORT), Handler) as httpd: print("serving at port", PORT) httpd.serve_forever() </code></pre> <h2 id="convert-csv-to-json">Convert CSV to JSON</h2> <pre><code data-lang="python">import csv import json csvfile = open('file.csv', 'r') jsonfile = open('file.json', 'w') fieldnames = ("FirstName","LastName","IDNumber","Message") reader = csv.DictReader( csvfile, fieldnames) for row in reader: json.dump(row, jsonfile) jsonfile.write('\n') </code></pre> <h2 id="generate-uuids">Generate uuids</h2> <pre><code data-lang="python">import uuid nbr = int(input("How many? ")) for _ in range(nbr): print(uuid.uuid4()) </code></pre> <h2 id="token-authorization-with-requests">Token authorization with Requests</h2> <pre><code data-lang="python">import requests import json TOKEN = "<your token>" URL= "https://api.github.com/repos/user/repo/releases/latest" headers_dict = {'Authorization': 'token %s' % TOKEN} r = requests.get(URL, headers=headers_dict) r_dict = r.json() r_json = json.dumps(r_dict) print(r_json) </code></pre> HTML cheatsheet Sun, 28 Jun 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/html/ https://lybekk.tech/cheatsheet/html/ <h2 id="html">HTML</h2> <h3 id="embed-plain-text-txt-files-in-html">Embed plain text (txt) files in .html</h3> <pre><code data-lang="html"><embed src="folder/file.txt" width="400" height="200"> </code></pre> <h3 id="style-embedded-elements">Style embedded elements</h3> <pre><code data-lang="html"><div style="margin: 0 auto; width:100%; height:400px; overflow: auto;"> <object type="text/html" data="file_name.txt" style="width:100%; height:400px; margin:1%;" /> </div> <p> <font color="#FFFFFF"> <embed src="filename.txt" width="x" height="y" /> </font> </p> </code></pre> Raspberry Pi Sun, 28 Jun 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/raspberry-pi/ https://lybekk.tech/cheatsheet/raspberry-pi/ <h2 id="misc">Misc.</h2> <h3 id="set-change-default-password">Set/change default password</h3> <p>When logged in as pi (the default user), enter <code>passwd</code> in a terminal</p> <h3 id="adding-users">Adding users</h3> <p>In a terminal, enter <code>sudo adduser username</code></p> <h2 id="configure-autostart-items">Configure autostart items</h2> <p>One method is to create a configuration file that is unique to the currently logged in user. First you need to edit this text file:</p> <pre><code data-lang="shell">sudo nano ~/.config/lxsession/LXDE/autostart </code></pre> <p>This file represents a list of commands to be executed when the GUI loads. It is usually blank when you first edit it so just add the applications you need to auto-load: @lxterminal @leafpad To save and exit the nano editor press CTRL-X, Y and then ENTER.</p> <h2 id="restart-apache-http-server">Restart Apache HTTP Server</h2> <pre><code data-lang="shell">sudo systemctl restart apache2 </code></pre> SQLite Thu, 25 Jun 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/sqlite/ https://lybekk.tech/cheatsheet/sqlite/ <h2 id="copy-specific-columns-from-one-table-and-insert-into-a-different-table">Copy specific columns from one table and insert into a different table</h2> <pre><code data-lang="sql">INSERT INTO destination_table (field1, field2) SELECT field1,field2 FROM 'source_table'; </code></pre> <h2 id="copy-content-in-one-column-to-another-column-within-the-same-table">Copy content in one column to another column within the same table</h2> <pre><code data-lang="sql">update tableName set destinationField = sourceField; </code></pre> <blockquote> <p>Warning! Replaces all content in destination fields</p> </blockquote> <h2 id="insert-uuids-in-empty-cells">Insert UUIDs in empty cells</h2> <pre><code data-lang="python">import sqlite3 import uuid db = 'database.db' sql_find_id = ''' SELECT idcolumn,rowid FROM tablename WHERE idcolumn IS NULL LIMIT 1 ''' sql_insert_uuid = ''' UPDATE tablename SET idcolumn=? WHERE rowid=? ''' sql_find_id_after = ''' SELECT idcolumn,rowid FROM tablename WHERE idcolumn=? ''' conn = sqlite3.connect(db) c = conn.cursor() c.execute(sql_find_id) nullornot = c.fetchone()[0] while nullornot == None: try: c.execute(sql_find_id) nullornot = c.fetchone()[0] except: break c.execute(sql_find_id) rowid = c.fetchone()[1] genuuid = str(uuid.uuid4()) c.execute(sql_insert_uuid, (genuuid,rowid,)) c.execute(sql_find_id_after, (genuuid,)) try: c.execute(sql_find_id) nullornot = c.fetchone()[0] except: print("All done") conn.commit() conn.close() </code></pre> Syncthing Thu, 25 Jun 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/syncthing/ https://lybekk.tech/cheatsheet/syncthing/ <h2 id="syncthing-on-a-lan">Syncthing on a LAN</h2> <p>Allowing Syncthing through the firewall enables sync between devices on a Local network (LAN) directly, instead of having to make roundtrips to Syncthing's Discovery servers.</p> <figure class="diagram"> <svg role="img" aria-label="Laptop and Cellphone sync directly over LAN WiFi; the LAN WiFi also reaches the Discovery server" width="318pt" height="188pt" viewBox="0.00 0.00 318.24 188.00" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"> <g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(4 184)"> <polygon fill="none" stroke="transparent" points="-4,4 -4,-184 314.24,-184 314.24,4 -4,4"/> <g id="node1" class="node"><ellipse fill="none" stroke="currentColor" cx="57.19" cy="-162" rx="42.79" ry="18"/> <text text-anchor="middle" x="57.19" y="-158.3" font-family="Times,serif" font-size="14.00">Laptop</text></g> <g id="node2" class="node"><ellipse fill="none" stroke="currentColor" cx="57.19" cy="-90" rx="55.49" ry="18"/> <text text-anchor="middle" x="57.19" y="-86.3" font-family="Times,serif" font-size="14.00">LAN WiFi</text></g> <g id="edge1" class="edge"><path fill="none" stroke="currentColor" d="M51.32,-144.05C50.5,-136.35 50.26,-127.03 50.59,-118.36"/> <polygon fill="currentColor" stroke="currentColor" points="54.09,-118.49 51.28,-108.28 47.11,-118.01 54.09,-118.49"/></g> <g id="edge4" class="edge"><path fill="none" stroke="currentColor" d="M63.11,-108.28C63.91,-116.03 64.14,-125.36 63.79,-134.01"/> <polygon fill="currentColor" stroke="currentColor" points="60.29,-133.83 63.07,-144.05 67.27,-134.33 60.29,-133.83"/></g> <g id="node3" class="node"><ellipse fill="none" stroke="currentColor" cx="57.19" cy="-18" rx="57.39" ry="18"/> <text text-anchor="middle" x="57.19" y="-14.3" font-family="Times,serif" font-size="14.00">Cellphone</text></g> <g id="edge2" class="edge"><path fill="none" stroke="currentColor" d="M51.32,-72.05C50.5,-64.35 50.26,-55.03 50.59,-46.36"/> <polygon fill="currentColor" stroke="currentColor" points="54.09,-46.49 51.28,-36.28 47.11,-46.01 54.09,-46.49"/></g> <g id="node4" class="node"><ellipse fill="none" stroke="currentColor" cx="221.19" cy="-18" rx="89.08" ry="18"/> <text text-anchor="middle" x="221.19" y="-14.3" font-family="Times,serif" font-size="14.00">Discovery server</text></g> <g id="edge5" class="edge"><path fill="none" stroke="currentColor" d="M89.6,-75.17C114.15,-64.69 148.2,-50.16 175.51,-38.5"/> <polygon fill="currentColor" stroke="currentColor" points="177.04,-41.65 184.86,-34.51 174.29,-35.21 177.04,-41.65"/></g> <g id="edge3" class="edge"><path fill="none" stroke="currentColor" d="M63.11,-36.28C63.91,-44.03 64.14,-53.36 63.79,-62.01"/> <polygon fill="currentColor" stroke="currentColor" points="60.29,-61.83 63.07,-72.05 67.27,-62.33 60.29,-61.83"/></g> </g> </svg> </figure> <h3 id="linux">Linux</h3> <p><em>Tested on Ubuntu and Raspbian</em></p> <p>Run these in the terminal</p> <pre><code data-lang="bash">sudo ufw allow syncthing sudo ufw allow syncthing-gui </code></pre> <p>Verfiy that firewall rules were added</p> <pre><code data-lang="bash">sudo ufw status verbose </code></pre> <h2 id="ignore-node-modules">Ignore Node Modules</h2> <p>Put these in the folders <code>.stignore</code>:</p> <pre><code>node_modules **node_modules </code></pre> Running PouchDB Server on Android Thu, 25 Jun 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/guide/pouchdb-server-termux/ https://lybekk.tech/guide/pouchdb-server-termux/ <p><strong>PouchDB Server</strong> is a drop-in replacement for CouchDB, using PouchDB and Node.js. <strong>Termux</strong> is an Android terminal emulator and Linux environment app that works directly with no rooting or setup required. With the ability to run a linux terminal on Android, we can get a running instance of PouchDB Server on it.</p> <h3 id="goal">Goal</h3> <p>Having a PouchDB Server running on your Android phone.</p> <h3 id="what-you-will-need">What you will need</h3> <p>An Android phone with <a rel="external" href="https://play.google.com/store/apps/details?id=com.termux&hl=en_US">Termux</a> installed</p> <h3 id="instructions">Instructions</h3> <p>At the command line in Termux, run the commands below in the following order:</p> <pre><code data-lang="bash">pkg install python pkg install nodejs npm -g install node-gyp npm install -g pouchdb-server </code></pre> <p><em>A ton of warnings and errors may pop up. These can be ignored as long as we get it up and running successfully.</em></p> <p>Finally, run:</p> <pre><code data-lang="bash">pouchdb-server --sqlite </code></pre> <p>If it didn't work, install SQLite:</p> <pre><code data-lang="bash">pkg install sqlite </code></pre> <p>If all goes well, the PouchDB Server admin interface should be available at <code>http://localhost:5984/_utils</code>, in any browser on your phone:</p> <h4 id="some-finishing-notes">Some finishing notes</h4> <ul> <li> <p><em>At first, PouchDB Server will only be available locally. To enable access from other devices connected to the same network access point, change configuration setting httpd bind_address to 0.0.0.0</em></p> </li> <li> <p><em>It starts in admin party-mode (no authentication = open to any one editing.). Be sure to create an admin user if the server is made available on the network to prevent unintended access.</em></p> </li> </ul> Bash cheatsheet Mon, 01 Jun 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/bash/ https://lybekk.tech/cheatsheet/bash/ <h2 id="find-files-with-grep">Find files with GREP</h2> <p>Search for a specific word, phrase or Regex in file contents.</p> <pre><code data-lang="bash"># Search for a specific word or phrase in a specific file grep "word" file.txt # Same as above, but limiting to one extension/suffix grep "word" *.txt # or using wildcard to search multiple files grep "word" * # As above, while traversing subdirectories grep -r "word" * # Case-Insensitive search (ignore case) grep -i "word" * </code></pre> <h2 id="read-x-last-lines-from-a-file">Read x last lines from a file</h2> <pre><code data-lang="bash"># example tail -100 /var/log/apache2/error.log </code></pre> <h2 id="copy-a-file">Copy a file</h2> <p>sudo cp /path/to/source/file.txt /path/for/destination/file.txt</p> <h2 id="recursively-search-for-filename">Recursively search for filename</h2> <pre><code data-lang="bash"># Add wildcard '*' on either side where required find . -name "yourfilename*" # Case insensitive find . -iname "yourfilename*" </code></pre> <h2 id="measure-temperature">Measure temperature</h2> <pre><code data-lang="bash"># If command is not found, install lm-sensors sudo apt install lm-sensors # Then run sensors # or sensors-detect </code></pre> <h2 id="tcptrack">TCPtrack</h2> <p>tcptrack displays the status of TCP connections that it sees on a given network interface. tcptrack monitors their state and displays information such as state, source/destination addresses and bandwidth usage in a sorted, updated list very much like the top(1) command.</p> <pre><code data-lang="bash"># If command is not found, install with sudo apt install tcptrack # Assumed network name - wlp2s0 - replace with your own. sudo tcptrack -r 1 -i wlp2s0 </code></pre> <h2 id="securely-erase-replace-free-space-on-disk">Securely erase/replace free space on disk</h2> <pre><code data-lang="bash"># Example. Replace 'Desktop' with desired path sfill -v Desktop/ </code></pre> <p><em>Skip -v for less verbose output</em></p> <h2 id="permissions">Permissions</h2> <h2 id="change-permissions">Change permissions</h2> <pre><code data-lang="bash"># Change owner user and group on a directory or file chown yourusername:yourgroup <directory or file> # Make a file editable for owner and group chmod 774 file.txt </code></pre> <h3 id="find-files-not-owned-by-user">Find files not owned by user</h3> <pre><code data-lang="bash">sudo find ~yourusername/ \! -user yourusername -print </code></pre> <h2 id="measure-wireless-wifi-wlan-signal-quality-and-strength">Measure wireless (WiFi/WLAN) signal quality and strength</h2> <pre><code data-lang="bash">iwconfig # Output example wlp2s0 IEEE 802.11 ESSID:"Network Name" Mode:Managed Frequency:2.472 GHz Access Point: 1D:B7:2C:37:0F:D0 Bit Rate=144.4 Mb/s Tx-Power=22 dBm Retry short limit:7 RTS thr:off Fragment thr:off Power Management:on Link Quality=53/70 Signal level=-57 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:991 Missed beacon:0 </code></pre> <p><em>Look for <code>Signal level</code>, this example outputs -57dbm, a good signal. Not excellent, but good.</em></p> <h2 id="count-words-in-a-plain-text-file">Count words in a plain text file</h2> <pre><code data-lang="bash">cat filename.txt | xargs -n1 | sort | uniq -c > newfilename.txt </code></pre> <h2 id="diff-find-differences-between-two-folders">Diff - Find differences between two folders</h2> <pre><code data-lang="bash">diff -r dir1 dir2 | grep dir1 | awk '{print $4}' > difference1.txt # For skipping pipe output to file diff -rq dir1 dir2 </code></pre> <h2 id="du-disk-usage">DU (disk usage)</h2> <h3 id="find-the-biggest-files-in-a-directory-and-subdirs">Find the biggest files in a directory (and subdirs)</h3> <pre><code data-lang="bash">du -Sh | sort -rh | head -20 </code></pre> <h3 id="directory-size">Directory size</h3> <pre><code data-lang="bash">du -sh * </code></pre> Couchbase cheatsheet Mon, 01 Jun 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/couchbase/ https://lybekk.tech/cheatsheet/couchbase/ <h2 id="couchbase-server">Couchbase Server</h2> <h3 id="starting-stopping">Starting & stopping</h3> <h4 id="linux-ubuntu-debian">Linux (Ubuntu/Debian)</h4> <p>In a terminal/console</p> <pre><code data-lang="shell">sudo systemctl start couchbase-server sudo systemctl stop couchbase-server </code></pre> <h4 id="powershell-windows">Powershell (Windows)</h4> <pre><code data-lang="shell">Stop-Service "CouchbaseServer" -PassThru Start-Service "CouchbaseServer" -PassThru # OR Restart-Service "CouchbaseServer" -PassThru </code></pre> <p><em>The -PassThru flag can be omitted. It just makes the console wait for the result before returning control of the console.</em></p> <h4 id="windows-cmd">Windows CMD</h4> <pre><code data-lang="shell">net stop CouchbaseServer net start CouchbaseServer </code></pre> <h3 id="adjusting-stats-collection">Adjusting stats collection</h3> <p>Log in as root or use sudo to change the Couchbase Server static configuration, which is located at: /opt/couchbase/etc/couchbase/static_config by default.</p> <p>Add the parameter grab_stats_every_n_ticks, 10, where 10 is the number of ticks. In the Couchbase Server environment, one tick is one second (default). It is recommended that the statistics collection be more frequent (and accurate). However, assign an appropriate tick value for your environment.</p> <p>Restart the Couchbase Server service.</p> <p>After restarting the Couchbase service, the statistics collection rate is changed.</p> <h2 id="couchbase-sync-gateway">Couchbase Sync Gateway</h2> <h3 id="starting-stopping-1">Starting & stopping</h3> <pre><code data-lang="shell">sudo service sync_gateway start sudo service sync_gateway stop </code></pre> <h3 id="adding-users">Adding users</h3> <p>This will add a normal user (I.E. not admin).</p> <pre><code data-lang="shell">curl -vX POST "http://localhost:4985/mydatabase/_user/" \ -H "accept: application/json" \ -H "Content-Type: application/json" \ -d '{"name": "user", "password": "<password>"}' </code></pre> <p><em>Users will get synced towards a connected instance of Couchbase Server</em></p> Kate Mon, 01 Jun 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/kate/ https://lybekk.tech/cheatsheet/kate/ <h2 id="fixing-kate-s-save-session-bug">Fixing Kate's 'save session' bug</h2> <p>If Kate is not saving sessions</p> <p>Make sure the active user own all files under <code>.kde</code></p> <pre><code data-lang="shell">sudo chown -R username:username /home/username/.kde </code></pre> <p>Open ~/.kde/share/config/katerc and verify if these are in there:</p> <pre><code>[General] Last Session=mysession.katesession Restore Window Configuration=true Session Exit=save </code></pre> <p><em>Note</em>: There has been a long outstanding bug where sometimes some of the settings are not properly saved.</p> Markdown syntax Mon, 01 Jun 2020 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/markdown/ https://lybekk.tech/cheatsheet/markdown/ <h2 id="markdown">Markdown</h2> <p>A more complete list of commonly used Markdown found <a rel="external" href="https://www.markdownguide.org/basic-syntax">here</a></p> <h2 id="definition-list">Definition List</h2> <pre> term : definition </pre> <h3 id="links-to-headings">Links to headings</h3> <p>You can make links to headings based on the heading text, for example:</p> <pre><code>### My Heading Lorem ipsum... [Reference](#my-heading) </code></pre> <h3 id="github-specific">GitHub specific</h3> <p>In order to create table of contents (TOC) in markdown files on GitHub, put this snippet anywhere you would want a TOC to be generated:</p> <pre><code>* TOC {:toc} </code></pre> Apache HTTP Server cheatsheet Wed, 29 May 2019 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/apache-http-server/ https://lybekk.tech/cheatsheet/apache-http-server/ <h2 id="config-file-location">Config file location</h2> <p>In Debian/Ubuntu distros: <code>/etc/apache2/apache2.conf</code></p> <h2 id="error-log-location">Error log location</h2> <p>Debian/Ubuntu: <code>/var/log/apache2/error.log</code></p> <h2 id="restarting">Restarting</h2> <pre><code data-lang="shell">sudo service apache2 restart # If that doesn't work, try this: sudo systemctl restart apache2 </code></pre> Termux cheatsheet Wed, 29 May 2019 00:00:00 +0000 Christoffer Lybekk https://lybekk.tech/cheatsheet/termux/ https://lybekk.tech/cheatsheet/termux/ <h2 id="termux-mariadb">Termux & MariaDB</h2> <p>How to run MariaDB, a drop-in alternative to MySQL, on Termux</p> <pre><code data-lang="bash"># Install MariaDB pkg mariadb # Run this multi-line command cd '/data/data/com.termux/files/usr' ; \ /data/data/com.termux/files/usr/bin/mysqld_safe \ --datadir='/data/data/com.termux/files/usr/var/lib/mysql' </code></pre> <h2 id="open-files-from-within-termux">Open files from within Termux</h2> <p>Open a file reachable by Termux, and view it in any Android app. I.E. send a file by email or view/edit an image in an editor.</p> <pre><code data-lang="shell">termux-open file.jpg </code></pre> <p>This will request the "open in" prompt. Handy for viewing images, PDF or any other file format not viewable in a terminal.</p> <h2 id="postgresql">PostgreSQL</h2> <h3 id="troubleshooting">Troubleshooting</h3> <p><em>Problem</em></p> <p>After installation, on database initialization PostgreSQL server is unable to start.</p> <p><strong>when running <code>$ initdb</code> the following exception is raised</strong></p> <samp> CANNOT LINK EXECUTABLE "/data/data/com.termux/files/usr/bin/postgres": library "libicui18n.so.67" not found no data was returned by command ""/data/data/com.termux/files/usr/bin/postgres" -V" initdb: error: The program "postgres" is needed by initdb but was not found in the same directory as "/data/data/com.termux/files/usr/bin/initdb". Check your installation. </samp> <p><em>Solution</em></p> <p><code>pkg upgrade</code></p> <h2 id="python">Python</h2> <h3 id="troubleshooting-1">Troubleshooting</h3> <p>If matplotlib fails to install: <code>pip3 install wheel</code></p> <p><em>Jupyter Notebook</em></p> <pre><code data-lang="shell">pkg install libzmq pip3 install jupyter </code></pre>