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Batch processing

• Install batcher Gimp plugin by copying its extracted folder to ~/.config/GIMP/3.0/plug-ins.
• Multiple images can be easily resized from its gui in gimp.

Multiple image to pdf

• Gimp not used because the pdf produced is too large on the disk.
• convert (from imagemagick) and img2pdf without the --imgsize option, produce pages of different sizes in the same pdf document.
• Without sorting by number, wildcards would sort files in an alphabetical order.

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Minimal plasma installation

$ sudo pacman -Sy plasma-desktop

Plasma applet for managing audio volume

Visible in lower-right corner:

$ sudo pacman -Sy plasma-pa

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Linking order

The dependent executable should appear before the libraries it depends on, as order is important (See 1).

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Kotlin

• Statically typed language.
• Outputs bytecode that runs on the JVM (like Java).

Build Automation tools for JVM projects

All of them are similar to CMake but for Java/Kotlin:

• Gradle: Build system for Android used for compilation, packaging (APK), and for dependency management. Preferred for Kotlin projects.

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What is it

An instrumentation tool for x86, Android..., that targets binary applications.

Usage

• To debug live processes.
• To execute your script inside another process.

Applications

• Frida is used for dynamic reverse engineering (i.e. analyze a program while software is running).
• Static reverse engineering software in contrast take binaries to dissect them.

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#include <limits.h>
#include <string.h>
#include <stdbool.h>
#include <gd.h>

#include "utils.h"

/**
 * Print password written beforehand on image with steganography_write.c
 * - GD documentation: https://libgd.github.io/manuals/2.1.1/files/preamble-txt.html

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#include <gd.h>

// C doesn't allow variable length arrays (even using a constant)
#define N_CORNERS 3

typedef struct {
  int x;
  int y;
} Point;

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#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

/**
 * Parse bitmap image to find RGB values at given row and column
 * Bitmap format: https://en.wikipedia.org/wiki/BMP_file_format
 * Tested input bitmap image saved in Gimp without color space information and in 24bits format

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File structure

• Libraries: Userland/Libraries/{LibC, LibGUI...}
• Games: Userland/Games/{Snake, Solitaire...}
• Applications: Userland/Applications/{Calculator, Calendar...}

Ninja

SerenityOS is built using CMake and Ninja.

• Target: output files of the build process (executables, libraries).
• Use Ninja with CMake: cmake -G Ninja (generates a build.ninja file)
• Build target: ninja

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Electronic components

• Breadboard: Rectangular plastic board with tiny holes to insert electronic components in them.
• Jump wire: Electrical wire used to interconnect components.
• Transistor: Used to amplify current, switch on/off the flow of current, and to construct logic gates.
• Diodes: Allows the flow of current in one direction & blocks the other direction (like a valve).
• Resistors: Limits the flow of current.
• Capacitor: Stores and releases electricity (like a temporary battery).
• LED: emits light when current flows through it.
• Arduino devices:
• Sensors: Used to monitor physical phenomena (e.g. temperature, humidity, motion, light...).