📝 write README.md

README.md

@@ -1,2 +1,112 @@
-# dynb
+# 🔃 dynb
-dynb - dynamic DNS update script for bash
+dynb - dynamic DNS update script, written in bash
+
+IPv4 (A) and IPv6 (AAAA) record updates are supported.
+<!-- TOC -->
+- [✨ Update Methods](#-update-methods)
+    - [APIs](#apis)
+    - [DynDNS2](#dyndns2)
+- [📦 Requirements](#-requirements)
+- [🚀 Installation](#-installation)
+- [⚙ Configuration](#-configuration)
+- [🏃 Run](#-run)
+- [⏰ Cron](#-cron)
+<!-- /TOC -->
+
+## ✨ Update Methods
+The following update methods are currently implemented:
+
+### APIs
+
+* INWX JSON-RPC-API  
+  Limitations:
+  - minimum TTL is 300 (5 minutes)
+
+### DynDNS2
+
+* INWX DynDNS2 protocol  
+  Limitations:
+  - minimum TTL is 60 (1 minute)
+  - one DynDNS account with one hostname is for free
+
+## 📦 Requirements
+
+* `curl` - The minimum requirement for running DynDNS2 operations
+
+essential for APIs:
+
+* `jq` - Command-line JSON processor
+
+optional requirement:
+
+* `getopt` for CLI parameter handling from [util-linux](https://pkgs.org/download/util-linux)
+
+## 🚀 Installation
+
+Download the latest release
+
+or simply clone this repo
+```
+git clone https://github.com/EV21/dynb.git
+```
+
+If you want to add the script to you PATH, run :point_down:
+```
+bash dynb.sh --link
+```
+This convenience function only works if `util-linux` is installed on your system.
+
+## ⚙ Configuration
+
+You can use a config in form of an `.env` file.
+Or if your system meets the relevant requirements you can use CLI parameters.
+
+Create `.env` in the app root directory or at `~/.local/share/dynb/.env`.
+```
+_dyn_domain=dyndns.example.com
+
+## service provider could be inwx
+_serviceProvider=inwx
+
+## update method options: domrobot, dyndns
+_update_method=domrobot
+
+## ip mode could be either: 4, 6 or dual for dualstack
+_ip_mode=dual
+
+## If you are using the DomRobot RPC-API enter your credentials for the web interface login here
+## If you are using the DynDNS2 protocol enter your credentials here
+_username=
+_password=
+```
+
+## 🏃 Run
+
+If you have a config file just run :point_down:
+```
+dynb
+```
+Alternatively you can use parameters if your system meets the relevant requirements. This example shows the long form parameter, there are also short ones.  
+Call the help function :point_down:
+```
+dynb --help
+```
+```
+dynb --ip-mode dualstack --update-method domrobot --domain dyndns.example.com --username user42 --password SuperSecretPassword
+```
+```
+dynb --ip-mode dualstack --update-method dyndns --provider inwx --domain dyndns.example.com --username user42 --password SuperSecretPassword
+```
+
+## ⏰ Cron
+To automatically call the script you can use cron.
+
+execute :point_down:
+```
+crontab -e
+```
+then enter :point_down: to run dynb every five minutes.
+```
+*/5 * * * * $HOME/.local/bin/dynb >> $HOME/.local/share/dynb/dynb-cron.log
+```
+Note, cron typically does not use the users PATH variable.