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Table Of Content

Skip to the relevant sections if needed.

• 2-min tutorial to do it the quick-and-dirty-way
• Concepts for resolving Git conflicts
• Setting up different editors / tool for using git mergetool
  • Finding out what mergetool editors are supported
• mergetool simple code example for vimdiff
  • Resolving conflict from a Git pull
• Other great references and tutorials

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package com.github.therapi.apidoc;

import java.util.List;

import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.module.jsonSchema.JsonSchema;
import com.fasterxml.jackson.module.jsonSchema.factories.SchemaFactoryWrapper;
import com.fasterxml.jackson.module.jsonSchema.factories.VisitorContext;

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Nix Flake MVP

Goals

• To provide Nix repositories with an easy and standard way to reference other Nix repositories.

• To allow such references to be queried and updated automatically.

• To provide a replacement for nix-channel, NIX_PATH and Hydra

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{ pkgsPath ? <nixpkgs> }:
let
  pkgs = import pkgsPath {};
  pkgsAarch64 = import pkgsPath { system = "aarch64-linux"; };

  iso = (pkgsAarch64.nixos {
    imports = [ (pkgsPath + "/nixos/modules/installer/cd-dvd/installation-cd-base.nix") ];
    users.users.root.openssh.authorizedKeys.keyFiles = [(builtins.fetchurl https://github.com/lheckemann.keys)];
  }).config.system.build.isoImage;

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How to compress PDF using ghostscript

As a developer, it bothers me when someone sends me a large pdf file compared to the number of pages. Recently, I recieved a 12MB scanned document for just one letter-sized page... so I got to googlin, like I usually do, and found ghostscript!

to learn more abot ghostscript (gs): https://www.ghostscript.com/

What we are interested in, is the gs command line tool, which provides many options for manipulating PDF, but we are interested in compressign those large PDF's into small yet legible documents.

credit goes to this answer on askubuntu forum: https://askubuntu.com/questions/3382/reduce-filesize-of-a-scanned-pdf/3387#3387?newreg=bceddef8bc334e5b88bbfd17a6e7c4f9

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PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

• -E: will describe the underlaying queries of the \ commands (cool for learning!)
• -l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

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# Adapted from @ryanorendorff's gist: https://gist.github.com/ryanorendorff/f5c96d9f363a0e390425c2d9588bbb9d

{ pkgs ? import <nixos> {} }:

let
  # The standard library in nixpkgs does not come with a *.agda-lib file, so we
  # generate it here.
  standard-library-agda-lib = pkgs.writeText "standard-library.agda-lib" ''
    name: standard-library
    include: ${pkgs.AgdaStdlib}/share/agda

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Install NixOS on Oracle Cloud over Ubuntu 18.04 (make sure to use Ubuntu 18.04 or this may not work)

# install useful tools
sudo apt-get update
sudo apt-get install --no-install-recommends -y nano mc git

# prepare /boot
sudo umount /boot/efi
sudo mv /boot /boot.bak

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# Module for configuring libvirt with static NixOS networking
# instead of using libvirt managed bridge.

{ config, lib, pkgs, ... }:
with lib;

let
  cfg = config.virtualisation.libvirtd.networking;
  v6Enabled = cfg.ipv6.network != null;
  v6PLen = toInt (elemAt (splitString "/" cfg.ipv6.network) 1);

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// example solution to remove comments from HTML.
// re: http://groups.google.com/group/jsoup/browse_thread/thread/419b5ac4be88b086

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Node;

public class RemoveComments {
    public static void main(String... args) {
        String h = "<div><!-- no --><p>Hello<!-- gone --></div>";