Update README.md

Dockerfiles/dockerfile.c_toolchain

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+FROM ubuntu:18.04
+RUN apt-get update && apt-get install -y vim gcc indent clang clang-format gdb binutils nasm xxd llvm lld
+WORKDIR /dmzOS
+ENTRYPOINT [ "bash" ]

README.md

@@ -1,24 +1,50 @@
 # dmzOS
-
+## About
 **dmzOS** is an operating system written by a group of computer enthusiasts gathered around [Decentrala](https://decentrala.org/). You are free to explore, learn, and contribute! 
 
-Description:
+### Description
 * Written from scratch in C and asm.
-* POSIX-compliant (as aspiring to [Stan Dard](https://wiki.osdev.org/Stan_Dard)).
+* POSIX-compliant (as we are aspiring to [Stan Dard](https://wiki.osdev.org/Stan_Dard)).
 * For the amd64 architecture.
 * Extensively documented.
 
-Goals:
+### Goals
 * Sharpen low-level programming skills.
 * Familiarize with amd64 architecture details.
 * Have fun along the way!
 
-Success criteria:
+### Success criteria
 * Run vim on the OS.
 
-Rules:
+### Rules
 * Please provide an adequate entry in the Wiki for each non-trivial code contribution.
 
-For additional information, please refer to the [Wiki](https://gitea.dmz.rs/sborovic/dmzOS/wiki).
+To learn more about the project, please refer to the [Wiki](https://gitea.dmz.rs/sborovic/dmzOS/wiki).
 
-TEST
+## DevOps
+### Development environment
+Essential software (plus dependencies) that are needed for the development are available through a custom Ubuntu-based Docker image (located in `Dockerfiles/dockerfile.c_toolchain` as well as on Docker Hub). This includes:
+- `gcc`: *The GNU Compiler Collection.*
+- `indent` GNU C code formatter.
+- `clang`: a compiler front end for the C, C++, Objective-C, and Objective-C++ programming languages
+- `clang-format`: a tool to automatically format C/C++/Objective-C code
+- `gdb`: *The GNU Debugger.*
+- `make`: a tool which controls the generation of executables and other non-source files of a program from the program's source files.
+- `objdump`: a command-line program for displaying various information about object files.
+- `nasm`: *The Netwide Assembler* is an assembler and disassembler for the Intel x86 architecture. 
+- `xxd`: a command-line program that may be used to manage, convert, and display binary files.
+- `ld`: *The GNU Linker*.
+- `lld`: a linker from the LLVM project that is a drop-in replacement for system linkers and runs much faster than them.
+- `vim`: a highly configurable text editor.
+> *Note*
+> A `.vimrc` file with a rule to format code on buffer save in line with *Kernighan and Ritchie style* (with 4-space indentation) comes pre-installed inside the image.
+
+Booting the latest `.iso` image of *dmzOS* is done using a [Dockerized QEMU](https://github.com/qemus/qemu-docker).
+
+#### Command cheatsheet
+* To get into a `bash` shell that is bound to the `dmzOS` directory:
+```docker
+docker-compose run --rm c_toolchain
+```
+> *Note*
+> Any changes in the container's `dmzOS` directory will be reflected in the local `dmzOS` directory.

config/.vimrc

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+set nobackup
+set nowritebackup
+set noswapfile
+set autoread
+
+set number relativenumber
+autocmd BufWritePost *.[ch] exec "!indent -kr -nut % && rm %~"

dmzOS/test/test.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+    if (argc < 2) {
+        printf("Please provide at least one argument\n");
+        exit(1);
+    };
+    printf("Hello, C!\n");
+    return 0;
+}

docker-compose.yml

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+version: '3.8'
+
+services:
+  c_toolchain:
+    build:
+      context: ./Dockerfiles
+      dockerfile: dockerfile.c_toolchain
+    container_name: c_toolchain
+    tty: true
+    stdin_open: true
+    volumes:
+      - ./dmzOS:/dmzOS
+      - ./config/.vimrc:/root/.vimrc