README.md: improved doc, added autoload details

README.md

@@ -5,16 +5,18 @@ its requirements turn it naturally to Linux systems. It has long been tested
 using Debian GNU/Linux, Devuan and different flavors of Ubuntu.
 
 ## Table of content
-  * [1. Getting started](#1-getting-started)
-  * [2. Design](#2-design)
-    + [2.1. Command line](#21-command-line)
-    + [2.2. Loading order and process](#22-loading-order-and-process)
-    + [2.3. Main configuration file](#23-main-configuration-file)
-    + [2.4. Naming conventions](#24-naming-conventions)
-    + [2.5. Basic module structure](#25-basic-module-structure)
-  * [3. Error code table](#3-error-code-table)
-  * [4. Contact and more information](#4-contact-and-more-information)
-
+- [init.sh](#initsh)
+  - [1. Getting started](#1-getting-started)
+  - [2. Design](#2-design)
+    - [2.1. Command line](#21-command-line)
+    - [2.2. Loading order and process](#22-loading-order-and-process)
+    - [2.3. Configuration files](#23-configuration-files)
+      - [2.3.1. Main configuration file](#231-main-configuration-file)
+      - [2.3.2. Automatically loaded configuration files](#232-automatically-loaded-configuration-files)
+    - [2.4. Naming conventions](#24-naming-conventions)
+    - [2.5. Basic module structure](#25-basic-module-structure)
+  - [3. Error code table](#3-error-code-table)
+  - [4. Contact and more information](#4-contact-and-more-information)
 
 ## 1. Getting started
 You should consider reading that document entirely before use. If you need
@@ -87,14 +89,18 @@ opposite the zzz_main_fct.sh file have to be loaded last, because it's widely
 using previously declared libraries.
 
 After that, a basic command line parameter treatment is done. That allows the
-use of --version and --help options in user space. Those options just display
+use of *--version* and *--help* options in user space. Those options display
 information and don't require any superuser rights and exit at that point of
 execution. Everything after that will require administrator rights and the
-script will exit with error at that point if not superuser.
+script will exit with error at that point if not superuser, unless the
+*--no-root-check* option have been given.
 
-Next will be the log file creation and the loading of configuration files. At
-this point a deeper analysis of command line option will be done, triggering
-errors in case of inconsistency or incompatible options.
+Next will be the log file creation and the loading of configuration files.
+Configuration files exists in two distinct categories. First system dependant
+configuration will be loaded automatically depending on your platform, then
+your own configuration. At this point a deeper analysis of command line option
+will be done, triggering errors in case of inconsistency or incompatible
+options.
 
 Finally, checking processes are launched in their declaration order (cf.
 configuration file). If no error occurs and after a confirmation prompt, final
@@ -104,7 +110,8 @@ Without the *--keep-going* option, any error will immediately stop execution.
 Some errors that could make the script impossible to execute will stop
 execution, even if the *--keep-going* option is provided.
 
-### 2.3. Main configuration file
+### 2.3. Configuration files
+#### 2.3.1. Main configuration file
 
 The main configuration file can be two different files. Either it's completely
 generic and will be named **init.conf.sh** in the "conf" directory, either it
@@ -128,6 +135,32 @@ so you can declare something on your organization configuration file and
 supersede it in your host configuration file. The only limit will be Bash
 capabilities in terms of variable manipulation.
 
+#### 2.3.2. Automatically loaded configuration files
+Those file are basically the system dependent part that assure compatibility
+with different Linux distributions. Some of those files are shipped with
+init.sh but you can add what you want to improve possibilities or to add support
+for a new distribution. init.sh understand the following possibilities in terms
+of OS detection:
+
+| Name        | Variable |                                                     |
+|:------------|:---------|:----------------------------------------------------|
+| **arch**    | SYS_ARCH | This is the system architecture, like x86_64, i386, arm64, etc. |
+| **dist**    | SYS_DIST | The name of the Linux distribution as reported by */etc/os-release*. |
+| **version** | SYS_VER  | Version of the distribution. If you run a rolling release and no version is provided by your */etc/os-release* file, the main version of the Linux kernel will be used (e.g. 5.4 for any version of 5.4. kernel branch). |
+| **codename**| SYS_CODE | If your distribution profide a version codename, it will be set with it. |
+
+The configuration files are loaded if exists in the following order:
+   1) arch.conf.sh
+   2) distro.conf.sh
+   3) distro-arch.conf.sh
+   4) distro-version.conf.sh
+   5) distro-codename.conf.sh (if *$SYS_CODE* defined)
+   6) distro-version-arch.conf.sh
+   7) distro-codename-arch.conf.sh (if *$SYS_CODE* defined)
+
+The loading of those files, if one exists, cannot be avoided. They all must be
+located in the *conf/auto* directory of the init.sh tree.
+
 ### 2.4. Naming conventions
 
 Because of internal mechanics, the dash character is forbidden in module names.