📝 update CHANGELOG.md

✨ add man page

.pre-commit-config.yaml

@@ -0,0 +1,17 @@
+repos:
+  - repo: https://github.com/syntaqx/git-hooks
+    rev: v0.0.17
+    hooks:
+    - id: shellcheck
+    - id: shfmt
+      args: 
+        - "-l" # list files whose formatting differs from shfmt's
+        - "-i 2" # indent: 0 for tabs (default), >0 for number of spaces
+        - "-ci" # switch cases will be indented
+        - "-w" # write result to file instead of stdout
+  - repo: https://github.com/executablebooks/mdformat
+    rev: 0.7.9
+    hooks:
+    - id: mdformat
+      additional_dependencies:
+      - mdformat-gfm # GitHub Flavored Markdown support

CHANGELOG.md

@@ -1,6 +1,71 @@
 # Changelog
 
 
+## 0.2.0 (2021-09-24)
+
+### New
+
+* :sparkles: enable parameter extensions for `docker run --interactive` [Eduard Veit]
+
+* :sparkles: add pre-commit hooks for markdown. [Eduard Veit]
+
+* :sparkles: change git hooks and add shfmt. [Eduard Veit]
+
+* :sparkles: add pre-commit git hook for shellcheck. [Eduard Veit]
+
+### Changes
+
+* :wrench: remove md-toc from pre-commit. [Eduard Veit]
+
+* :wrench: handle dns server selection. [Eduard Veit]
+
+### Documentation
+
+* :memo: update CHANGELOG.md. [Eduard Veit]
+
+* :memo: document docker parameters. [Eduard Veit]
+
+* :memo: change default dns server setting. [Eduard Veit]
+
+* :memo: update CHANGELOG. [Eduard Veit]
+
+* :memo: update README.md. [Eduard Veit]
+
+### Other
+
+* :art: lint README.md. [Eduard Veit]
+
+* :art: add shfmt params to pre-commit check. [Eduard Veit]
+
+* :art: fix shell style. [Eduard Veit]
+
+* :recycle: seperate parsing logic. [Eduard Veit]
+
+* :recycle: normalizing pre-commit configuration to a top-level map. [Eduard Veit]
+
+* :recycle: refactorings. [Eduard Veit]
+
+* Refactor: :recycle: remove unused help message. [Eduard Veit]
+
+
+## 0.1.2 (2021-04-23)
+
+### Documentation
+
+* :memo: document environment variables. [Eduard Veit]
+
+### Other
+
+* :recycle: refactor: method extractions and other beautifications. [Eduard Veit]
+
+
+## 0.1.1 (2021-04-23)
+
+### Fix
+
+* :bug: fix loop and error handling in case of connection issues. [Eduard Veit]
+
+
 ## 0.1.0 (2021-04-22)
 
 ### New

Dockerfile

@@ -1,5 +1,12 @@
 FROM alpine:latest
-RUN apk update && apk add bash curl jq bind-tools
+RUN \
+apk update \
+&& \
+apk add \
+bash \
+curl \
+jq \
+bind-tools
 WORKDIR /usr/src/app
 COPY . .
-CMD /bin/bash /usr/src/app/dynb.sh
+ENTRYPOINT ["/bin/bash", "/usr/src/app/dynb.sh"]

README.md

@@ -1,8 +1,11 @@
 # 🔃 DynB
+
 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)
@@ -11,45 +14,52 @@ IPv4 (A) and IPv6 (AAAA) record updates are supported.
 - [⚙ Configuration](#-configuration)
 - [🏃 Run](#-run)
 - [⏰ Cron](#-cron)
-- [⏰ docker](#-docker)
+  - [loop mode](#loop-mode)
+  - [crontab](#crontab)
+- [🐟 docker](#-docker)
+- [environment variables](#environment-variables)
+
 <!-- /TOC -->
 
 ## ✨ Update Methods
+
 The following update methods are currently implemented:
 
 ### APIs
 
-* INWX.com Domrobot JSON-RPC-API  
+- INWX.com Domrobot JSON-RPC-API\
   Limitations:
   - minimum TTL is 300 (5 minutes)
 
 ### DynDNS2
 
-* INWX.com  
+- INWX.com
-* deSEC.io (dedyn.io)  
+- deSEC.io (dedyn.io)
-* DuckDNS.org  
+- DuckDNS.org
-* dynv6.com  
+- dynv6.com
 
 ## 📦 Requirements
 
-* `curl` - The minimum requirement for all API requests.
+- `curl` - The minimum requirement for all API requests.
-* `dig` - You can get it by installing `dnsutils` (debian/ubuntu/ArchLinux), `bind-utils` (CentOS/RHEL), `bind-tools` (Alpine)
+- `dig` - You can get it by installing `dnsutils` (debian/ubuntu/ArchLinux), `bind-utils` (CentOS/RHEL), `bind-tools` (Alpine)
 
 also essential if you are using other APIs:
 
-* `jq` - Command-line JSON processor
+- `jq` - Command-line JSON processor
 
 ## 🚀 Installation
 
 Download the latest release
 
 or simply clone this repo
-```
+
+```shell
 git clone https://github.com/EV21/dynb.git
 ```
 
 If you want to add the script to you PATH, run :point_down:
-```
+
+```shell
 bash dynb.sh --link
 ```
 
@@ -59,7 +69,8 @@ You can use a config in form of an `.env` file.
 Or you can just use CLI parameters.
 
 Create `.env` in the app root directory or at `~/.local/share/dynb/.env`.
-```
+
+```bash
 DYNB_DYN_DOMAIN=dyndns.example.com
 
 ## service provider could be deSEC, duckdns, dynv6, inwx
@@ -82,18 +93,23 @@ DYNB_TOKEN=
 ## 🏃 Run
 
 If you have a config file just run :point_down:
-```
+
+```bash
 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.  
+
+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:
-```
+
+```bash
 dynb --help
 ```
-```
+
+```bash
 dynb --ip-mode dualstack --update-method domrobot --domain dyndns.example.com --username user42 --password SuperSecretPassword
 ```
-```
+
+```bash
 dynb --ip-mode dualstack --update-method dyndns --provider inwx --domain dyndns.example.com --username user42 --password SuperSecretPassword
 ```
 
@@ -108,18 +124,29 @@ Just use the parameter `--interval 60` or the environment variable `DYNB_INTERVA
 ### crontab
 
 execute :point_down:
-```
+
+```bash
 crontab -e
 ```
+
 then enter :point_down: to run dynb every five minutes.
-```
+
+```bash
 */5 * * * * $HOME/.local/bin/dynb >> $HOME/.local/share/dynb/dynb-cron.log
 ```
+
+alternative with docker and parameters::
+
+```bash
+*/5 * * * * docker run --interactive --tty --rm --network host ev21/dynb:latest --ip-mode 64 --update-method domrobot --domain dyndns.example.com --username user42 --password SuperSecretPassword
+```
+
 Note, cron typically does not use the users PATH variable.
 
 ## 🐟 docker
 
-This is an example of a `docker-compose.yml` file. If you are using IPv6 make sure the routing works properly with your docker container.
+This is an example of a `docker-compose.yml` file. If you are using IPv6 make sure the routing works properly with your docker container. Note: [IPv6 networking](https://docs.docker.com/config/daemon/ipv6/) is only supported on Docker daemons running on Linux hosts.
+
 ```yaml
 version: '3.4'
 
@@ -140,3 +167,20 @@ services:
       - DYNB_PASSWORD=SuperSecretPassword
       - DYNB_INTERVAL=60
 ```
+
+## environment variables
+
+| variable              | default value   | description                                                                                                    |
+| --------------------- | --------------- | -------------------------------------------------------------------------------------------------------------- |
+| DYNB_DYN_DOMAIN       | undefined       | required; `dyndns.example.com`                                                                                 |
+| DYNB_SERVICE_PROVIDER | undefined       | required; `deSEC`, `duckdns`, `dynv6`, `inwx`                                                                  |
+| DYNB_UPDATE_METHOD    | undefined       | required; `dyndns` or `domrobot` (with inwx)                                                                   |
+| DYNB_IP_MODE          | undefined       | required; `4`, `6` or `64` for both                                                                            |
+| DYNB_USERNAME         | undefined       | the requirement depends on your provider and the update method                                                 |
+| DYNB_PASSWORD         | undefined       | the requirement depends on your provider and the update method                                                 |
+| DYNB_TOKEN            | undefined       | the requirement depends on your provider and the update method                                                 |
+| DYNB_INTERVAL         | undefined       | without this setting the script/docker container will run one time and exits                                   |
+| DYNB_DEBUG            | undefined       | more console outputs                                                                                           |
+| DYNB_IPv4_CHECK_SITE  | api64.ipify.org | You need a website or Web-API that outputs your remote IP                                                      |
+| DYNB_IPv6_CHECK_SITE  | api64.ipify.org | You need a website or Web-API that outputs your remote IP                                                      |
+| DYNB_DNS_CHECK_SERVER | undefined       | If you are using a local DNS Resolver/Server make sure it answers with the public answer or set another server |

dynb-parsing-template.m4

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+# m4_ignore(
+echo "This is just a script template for argbash, not the script." >&2
+exit 11  #)Created by argbash-init v2.10.0
+# Rearrange the order of options below according to what you would like to see in the help message.
+# ARG_OPTIONAL_BOOLEAN([version],[v],[outputs the client version],[off])
+# ARG_OPTIONAL_BOOLEAN([link],[l],[links to your script at ~/.local/bin/dynb],[off])
+# ARG_OPTIONAL_BOOLEAN([reset],[r],[deletes the client blocking status file],[off])
+# ARG_OPTIONAL_BOOLEAN([debug],[],[enables debug mode],[off])
+# ARG_OPTIONAL_SINGLE([update-method],[m],[choose if you want to use DynDNS2 or the DomRobot RPC-API],[])
+# ARG_OPTIONAL_SINGLE([ip-mode],[i],[updates type A (IPv4) and AAAA (IPv6) records],[])
+# ARG_OPTIONAL_SINGLE([domain],[d],[set the domain you want to update],[])
+# ARG_OPTIONAL_SINGLE([service-provider],[s],[set your provider in case you are using DynDNS2],[])
+# ARG_OPTIONAL_SINGLE([username],[u],[depends on your selected update method and your provider],[])
+# ARG_OPTIONAL_SINGLE([password],[p],[depends on your selected update method and your provider],[])
+# ARG_OPTIONAL_SINGLE([token],[t],[depends on your selected update method and your provider],[])
+# ARG_OPTIONAL_SINGLE([interval],[],[choose the seconds interval to run the script in a loop, minimum is 60],[])
+# ARG_HELP([DynB - dynamic DNS update script for bash])
+# ARGBASH_GO
+
+# [ <-- needed because of Argbash
+
+# ] <-- needed because of Argbash

dynb-parsing.sh

@@ -0,0 +1,297 @@
+#!/bin/bash
+
+# Created by argbash-init v2.10.0
+# Rearrange the order of options below according to what you would like to see in the help message.
+# ARG_OPTIONAL_BOOLEAN([version],[v],[outputs the client version],[off])
+# ARG_OPTIONAL_BOOLEAN([link],[l],[links to your script at ~/.local/bin/dynb],[off])
+# ARG_OPTIONAL_BOOLEAN([reset],[r],[deletes the client blocking status file],[off])
+# ARG_OPTIONAL_BOOLEAN([debug],[],[enables debug mode],[off])
+# ARG_OPTIONAL_SINGLE([update-method],[m],[choose if you want to use DynDNS2 or the DomRobot RPC-API],[])
+# ARG_OPTIONAL_SINGLE([ip-mode],[i],[updates type A (IPv4) and AAAA (IPv6) records],[])
+# ARG_OPTIONAL_SINGLE([domain],[d],[set the domain you want to update],[])
+# ARG_OPTIONAL_SINGLE([service-provider],[s],[set your provider in case you are using DynDNS2],[])
+# ARG_OPTIONAL_SINGLE([username],[u],[depends on your selected update method and your provider],[])
+# ARG_OPTIONAL_SINGLE([password],[p],[depends on your selected update method and your provider],[])
+# ARG_OPTIONAL_SINGLE([token],[t],[depends on your selected update method and your provider],[])
+# ARG_OPTIONAL_SINGLE([interval],[],[choose the seconds interval to run the script in a loop, minimum is 60],[])
+# ARG_HELP([DynB - dynamic DNS update script for bash])
+# ARGBASH_GO()
+# needed because of Argbash --> m4_ignore([
+### START OF CODE GENERATED BY Argbash v2.10.0 one line above ###
+# Argbash is a bash code generator used to get arguments parsing right.
+# Argbash is FREE SOFTWARE, see https://argbash.io for more info
+
+
+# # When called, the process ends.
+# Args:
+# 	$1: The exit message (print to stderr)
+# 	$2: The exit code (default is 1)
+# if env var _PRINT_HELP is set to 'yes', the usage is print to stderr (prior to $1)
+# Example:
+# 	test -f "$_arg_infile" || _PRINT_HELP=yes die "Can't continue, have to supply file as an argument, got '$_arg_infile'" 4
+die()
+{
+	local _ret="${2:-1}"
+	test "${_PRINT_HELP:-no}" = yes && print_help >&2
+	echo "$1" >&2
+	exit "${_ret}"
+}
+
+
+# Function that evaluates whether a value passed to it begins by a character
+# that is a short option of an argument the script knows about.
+# This is required in order to support getopts-like short options grouping.
+begins_with_short_option()
+{
+	local first_option all_short_options='vlrmidsupth'
+	first_option="${1:0:1}"
+	test "$all_short_options" = "${all_short_options/$first_option/}" && return 1 || return 0
+}
+
+# THE DEFAULTS INITIALIZATION - OPTIONALS
+_arg_version="off"
+_arg_link="off"
+_arg_reset="off"
+_arg_debug="off"
+_arg_update_method=
+_arg_ip_mode=
+_arg_domain=
+_arg_service_provider=
+_arg_username=
+_arg_password=
+_arg_token=
+_arg_interval=
+
+
+# Function that prints general usage of the script.
+# This is useful if users asks for it, or if there is an argument parsing error (unexpected / spurious arguments)
+# and it makes sense to remind the user how the script is supposed to be called.
+print_help()
+{
+	printf '%s\n' "DynB - dynamic DNS update script for bash"
+	printf 'Usage: %s [-v|--(no-)version] [-l|--(no-)link] [-r|--(no-)reset] [--(no-)debug] [-m|--update-method <arg>] [-i|--ip-mode <arg>] [-d|--domain <arg>] [-s|--service-provider <arg>] [-u|--username <arg>] [-p|--password <arg>] [-t|--token <arg>] [--interval <arg>] [-h|--help]\n' "$0"
+	printf '\t%s\n' "-v, --version, --no-version: outputs the client version (off by default)"
+	printf '\t%s\n' "-l, --link, --no-link: links to your script at ~/.local/bin/dynb (off by default)"
+	printf '\t%s\n' "-r, --reset, --no-reset: deletes the client blocking status file (off by default)"
+	printf '\t%s\n' "--debug, --no-debug: enables debug mode (off by default)"
+	printf '\t%s\n' "-m, --update-method: choose if you want to use DynDNS2 or the DomRobot RPC-API (no default)"
+	printf '\t%s\n' "-i, --ip-mode: updates type A (IPv4) and AAAA (IPv6) records (no default)"
+	printf '\t%s\n' "-d, --domain: set the domain you want to update (no default)"
+	printf '\t%s\n' "-s, --service-provider: set your provider in case you are using DynDNS2 (no default)"
+	printf '\t%s\n' "-u, --username: depends on your selected update method and your provider (no default)"
+	printf '\t%s\n' "-p, --password: depends on your selected update method and your provider (no default)"
+	printf '\t%s\n' "-t, --token: depends on your selected update method and your provider (no default)"
+	printf '\t%s\n' "--interval: choose the seconds interval to run the script in a loop, minimum is 60 (no default)"
+	printf '\t%s\n' "-h, --help: Prints help"
+}
+
+
+# The parsing of the command-line
+parse_commandline()
+{
+	while test $# -gt 0
+	do
+		_key="$1"
+		case "$_key" in
+			# The version argurment doesn't accept a value,
+			# we expect the --version or -v, so we watch for them.
+			-v|--no-version|--version)
+				_arg_version="on"
+				test "${1:0:5}" = "--no-" && _arg_version="off"
+				;;
+			# We support getopts-style short arguments clustering,
+			# so as -v doesn't accept value, other short options may be appended to it, so we watch for -v*.
+			# After stripping the leading -v from the argument, we have to make sure
+			# that the first character that follows coresponds to a short option.
+			-v*)
+				_arg_version="on"
+				_next="${_key##-v}"
+				if test -n "$_next" -a "$_next" != "$_key"
+				then
+					{ begins_with_short_option "$_next" && shift && set -- "-v" "-${_next}" "$@"; } || die "The short option '$_key' can't be decomposed to ${_key:0:2} and -${_key:2}, because ${_key:0:2} doesn't accept value and '-${_key:2:1}' doesn't correspond to a short option."
+				fi
+				;;
+			# See the comment of option '--version' to see what's going on here - principle is the same.
+			-l|--no-link|--link)
+				_arg_link="on"
+				test "${1:0:5}" = "--no-" && _arg_link="off"
+				;;
+			# See the comment of option '-v' to see what's going on here - principle is the same.
+			-l*)
+				_arg_link="on"
+				_next="${_key##-l}"
+				if test -n "$_next" -a "$_next" != "$_key"
+				then
+					{ begins_with_short_option "$_next" && shift && set -- "-l" "-${_next}" "$@"; } || die "The short option '$_key' can't be decomposed to ${_key:0:2} and -${_key:2}, because ${_key:0:2} doesn't accept value and '-${_key:2:1}' doesn't correspond to a short option."
+				fi
+				;;
+			# See the comment of option '--version' to see what's going on here - principle is the same.
+			-r|--no-reset|--reset)
+				_arg_reset="on"
+				test "${1:0:5}" = "--no-" && _arg_reset="off"
+				;;
+			# See the comment of option '-v' to see what's going on here - principle is the same.
+			-r*)
+				_arg_reset="on"
+				_next="${_key##-r}"
+				if test -n "$_next" -a "$_next" != "$_key"
+				then
+					{ begins_with_short_option "$_next" && shift && set -- "-r" "-${_next}" "$@"; } || die "The short option '$_key' can't be decomposed to ${_key:0:2} and -${_key:2}, because ${_key:0:2} doesn't accept value and '-${_key:2:1}' doesn't correspond to a short option."
+				fi
+				;;
+			# See the comment of option '--version' to see what's going on here - principle is the same.
+			--no-debug|--debug)
+				_arg_debug="on"
+				test "${1:0:5}" = "--no-" && _arg_debug="off"
+				;;
+			# We support whitespace as a delimiter between option argument and its value.
+			# Therefore, we expect the --update-method or -m value.
+			# so we watch for --update-method and -m.
+			# Since we know that we got the long or short option,
+			# we just reach out for the next argument to get the value.
+			-m|--update-method)
+				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
+				_arg_update_method="$2"
+				shift
+				;;
+			# We support the = as a delimiter between option argument and its value.
+			# Therefore, we expect --update-method=value, so we watch for --update-method=*
+			# For whatever we get, we strip '--update-method=' using the ${var##--update-method=} notation
+			# to get the argument value
+			--update-method=*)
+				_arg_update_method="${_key##--update-method=}"
+				;;
+			# We support getopts-style short arguments grouping,
+			# so as -m accepts value, we allow it to be appended to it, so we watch for -m*
+			# and we strip the leading -m from the argument string using the ${var##-m} notation.
+			-m*)
+				_arg_update_method="${_key##-m}"
+				;;
+			# See the comment of option '--update-method' to see what's going on here - principle is the same.
+			-i|--ip-mode)
+				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
+				_arg_ip_mode="$2"
+				shift
+				;;
+			# See the comment of option '--update-method=' to see what's going on here - principle is the same.
+			--ip-mode=*)
+				_arg_ip_mode="${_key##--ip-mode=}"
+				;;
+			# See the comment of option '-m' to see what's going on here - principle is the same.
+			-i*)
+				_arg_ip_mode="${_key##-i}"
+				;;
+			# See the comment of option '--update-method' to see what's going on here - principle is the same.
+			-d|--domain)
+				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
+				_arg_domain="$2"
+				shift
+				;;
+			# See the comment of option '--update-method=' to see what's going on here - principle is the same.
+			--domain=*)
+				_arg_domain="${_key##--domain=}"
+				;;
+			# See the comment of option '-m' to see what's going on here - principle is the same.
+			-d*)
+				_arg_domain="${_key##-d}"
+				;;
+			# See the comment of option '--update-method' to see what's going on here - principle is the same.
+			-s|--service-provider)
+				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
+				_arg_service_provider="$2"
+				shift
+				;;
+			# See the comment of option '--update-method=' to see what's going on here - principle is the same.
+			--service-provider=*)
+				_arg_service_provider="${_key##--service-provider=}"
+				;;
+			# See the comment of option '-m' to see what's going on here - principle is the same.
+			-s*)
+				_arg_service_provider="${_key##-s}"
+				;;
+			# See the comment of option '--update-method' to see what's going on here - principle is the same.
+			-u|--username)
+				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
+				_arg_username="$2"
+				shift
+				;;
+			# See the comment of option '--update-method=' to see what's going on here - principle is the same.
+			--username=*)
+				_arg_username="${_key##--username=}"
+				;;
+			# See the comment of option '-m' to see what's going on here - principle is the same.
+			-u*)
+				_arg_username="${_key##-u}"
+				;;
+			# See the comment of option '--update-method' to see what's going on here - principle is the same.
+			-p|--password)
+				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
+				_arg_password="$2"
+				shift
+				;;
+			# See the comment of option '--update-method=' to see what's going on here - principle is the same.
+			--password=*)
+				_arg_password="${_key##--password=}"
+				;;
+			# See the comment of option '-m' to see what's going on here - principle is the same.
+			-p*)
+				_arg_password="${_key##-p}"
+				;;
+			# See the comment of option '--update-method' to see what's going on here - principle is the same.
+			-t|--token)
+				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
+				_arg_token="$2"
+				shift
+				;;
+			# See the comment of option '--update-method=' to see what's going on here - principle is the same.
+			--token=*)
+				_arg_token="${_key##--token=}"
+				;;
+			# See the comment of option '-m' to see what's going on here - principle is the same.
+			-t*)
+				_arg_token="${_key##-t}"
+				;;
+			# See the comment of option '--update-method' to see what's going on here - principle is the same.
+			--interval)
+				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
+				_arg_interval="$2"
+				shift
+				;;
+			# See the comment of option '--update-method=' to see what's going on here - principle is the same.
+			--interval=*)
+				_arg_interval="${_key##--interval=}"
+				;;
+			# See the comment of option '--version' to see what's going on here - principle is the same.
+			-h|--help)
+				print_help
+				exit 0
+				;;
+			# See the comment of option '-v' to see what's going on here - principle is the same.
+			-h*)
+				print_help
+				exit 0
+				;;
+			*)
+				_PRINT_HELP=yes die "FATAL ERROR: Got an unexpected argument '$1'" 1
+				;;
+		esac
+		shift
+	done
+}
+
+# Now call all the functions defined above that are needed to get the job done
+parse_commandline "$@"
+
+# OTHER STUFF GENERATED BY Argbash
+
+### END OF CODE GENERATED BY Argbash (sortof) ### ])
+# [ <-- needed because of Argbash
+
+
+# vvv  PLACE YOUR CODE HERE  vvv
+
+# PUT YOUR CODE HERE
+
+# ^^^  TERMINATE YOUR CODE BEFORE THE BOTTOM ARGBASH MARKER  ^^^
+
+# ] <-- needed because of Argbash

dynb.sh

@@ -41,7 +41,7 @@ _ipv4_checker=api64.ipify.org
 _ipv6_checker=api64.ipify.org
 
 ## An exernal DNS check server prevents wrong info from local DNS servers/resolvers
-_DNS_checkServer=1.1.1.1
+_DNS_checkServer=
 
 ## if you are actively using multiple network interfaces you might want to specify this
 ## normally the default value is okay
@@ -65,7 +65,7 @@ _response=
 _statusHostname=
 _statusUsername=
 _statusPassword=
-_version=0.1.0
+_version=0.1.2
 _userAgent="DynB/$_version github.com/EV21/dynb"
 _configFile=$HOME/.local/share/dynb/.env
 _statusFile=/tmp/dynb.status
@@ -73,262 +73,6 @@ _debug=0
 _minimum_looptime=60
 _loopMode=0
 
-# Created by argbash-init v2.10.0
-# Rearrange the order of options below according to what you would like to see in the help message.
-# ARG_OPTIONAL_BOOLEAN([version],[v],[outputs the client version],[off])
-# ARG_OPTIONAL_BOOLEAN([link],[l],[links to your script at ~/.local/bin/dynb],[off])
-# ARG_OPTIONAL_BOOLEAN([reset],[r],[deletes the client blocking status file],[off])
-# ARG_OPTIONAL_BOOLEAN([debug],[],[enables debug mode],[off])
-# ARG_OPTIONAL_SINGLE([update-method],[m],[choose if you want to use DynDNS2 or the DomRobot RPC-API],[])
-# ARG_OPTIONAL_SINGLE([ip-mode],[i],[updates type A (IPv4) and AAAA (IPv6) records],[])
-# ARG_OPTIONAL_SINGLE([domain],[d],[set the domain you want to update],[])
-# ARG_OPTIONAL_SINGLE([service-provider],[s],[set your provider in case you are using DynDNS2],[])
-# ARG_OPTIONAL_SINGLE([username],[u],[depends on your selected update method and your provider],[])
-# ARG_OPTIONAL_SINGLE([password],[p],[depends on your selected update method and your provider],[])
-# ARG_OPTIONAL_SINGLE([token],[t],[depends on your selected update method and your provider],[])
-# ARG_OPTIONAL_SINGLE([interval],[],[choose the seconds interval to run the script in a loop, minimum is 60],[])
-# ARG_HELP([DynB - dynamic DNS update script for bash])
-# ARGBASH_GO()
-# needed because of Argbash --> m4_ignore([
-### START OF CODE GENERATED BY Argbash v2.10.0 one line above ###
-# Argbash is a bash code generator used to get arguments parsing right.
-# Argbash is FREE SOFTWARE, see https://argbash.io for more info
-
-
-die()
-{
-	local _ret="${2:-1}"
-	test "${_PRINT_HELP:-no}" = yes && print_help >&2
-	echo "$1" >&2
-	exit "${_ret}"
-}
-
-
-begins_with_short_option()
-{
-	local first_option all_short_options='vlrmidsupth'
-	first_option="${1:0:1}"
-	test "$all_short_options" = "${all_short_options/$first_option/}" && return 1 || return 0
-}
-
-# THE DEFAULTS INITIALIZATION - OPTIONALS
-_arg_version="off"
-_arg_link="off"
-_arg_reset="off"
-_arg_debug="off"
-_arg_update_method=
-_arg_ip_mode=
-_arg_domain=
-_arg_service_provider=
-_arg_username=
-_arg_password=
-_arg_token=
-_arg_interval=
-
-
-print_help()
-{
-	printf '%s\n' "DynB - dynamic DNS update script for bash"
-	printf 'Usage: %s [-v|--(no-)version] [-l|--(no-)link] [-r|--(no-)reset] [--(no-)debug] [-m|--update-method <arg>] [-i|--ip-mode <arg>] [-d|--domain <arg>] [-s|--service-provider <arg>] [-u|--username <arg>] [-p|--password <arg>] [-t|--token <arg>] [--interval <arg>] [-h|--help]\n' "$0"
-	printf '\t%s\n' "-v, --version, --no-version: outputs the client version (off by default)"
-	printf '\t%s\n' "-l, --link, --no-link: links to your script at ~/.local/bin/dynb (off by default)"
-	printf '\t%s\n' "-r, --reset, --no-reset: deletes the client blocking status file (off by default)"
-	printf '\t%s\n' "--debug, --no-debug: enables debug mode (off by default)"
-	printf '\t%s\n' "-m, --update-method: choose if you want to use DynDNS2 or the DomRobot RPC-API (no default)"
-	printf '\t%s\n' "-i, --ip-mode: updates type A (IPv4) and AAAA (IPv6) records (no default)"
-	printf '\t%s\n' "-d, --domain: set the domain you want to update (no default)"
-	printf '\t%s\n' "-s, --service-provider: set your provider in case you are using DynDNS2 (no default)"
-	printf '\t%s\n' "-u, --username: depends on your selected update method and your provider (no default)"
-	printf '\t%s\n' "-p, --password: depends on your selected update method and your provider (no default)"
-	printf '\t%s\n' "-t, --token: depends on your selected update method and your provider (no default)"
-	printf '\t%s\n' "--interval: choose the seconds interval to run the script in a loop, minimum is 60 (no default)"
-	printf '\t%s\n' "-h, --help: Prints help"
-}
-
-
-parse_commandline()
-{
-	while test $# -gt 0
-	do
-		_key="$1"
-		case "$_key" in
-			-v|--no-version|--version)
-				_arg_version="on"
-				test "${1:0:5}" = "--no-" && _arg_version="off"
-				;;
-			-v*)
-				_arg_version="on"
-				_next="${_key##-v}"
-				if test -n "$_next" -a "$_next" != "$_key"
-				then
-					{ begins_with_short_option "$_next" && shift && set -- "-v" "-${_next}" "$@"; } || die "The short option '$_key' can't be decomposed to ${_key:0:2} and -${_key:2}, because ${_key:0:2} doesn't accept value and '-${_key:2:1}' doesn't correspond to a short option."
-				fi
-				;;
-			-l|--no-link|--link)
-				_arg_link="on"
-				test "${1:0:5}" = "--no-" && _arg_link="off"
-				;;
-			-l*)
-				_arg_link="on"
-				_next="${_key##-l}"
-				if test -n "$_next" -a "$_next" != "$_key"
-				then
-					{ begins_with_short_option "$_next" && shift && set -- "-l" "-${_next}" "$@"; } || die "The short option '$_key' can't be decomposed to ${_key:0:2} and -${_key:2}, because ${_key:0:2} doesn't accept value and '-${_key:2:1}' doesn't correspond to a short option."
-				fi
-				;;
-			-r|--no-reset|--reset)
-				_arg_reset="on"
-				test "${1:0:5}" = "--no-" && _arg_reset="off"
-				;;
-			-r*)
-				_arg_reset="on"
-				_next="${_key##-r}"
-				if test -n "$_next" -a "$_next" != "$_key"
-				then
-					{ begins_with_short_option "$_next" && shift && set -- "-r" "-${_next}" "$@"; } || die "The short option '$_key' can't be decomposed to ${_key:0:2} and -${_key:2}, because ${_key:0:2} doesn't accept value and '-${_key:2:1}' doesn't correspond to a short option."
-				fi
-				;;
-			--no-debug|--debug)
-				_arg_debug="on"
-				test "${1:0:5}" = "--no-" && _arg_debug="off"
-				;;
-			-m|--update-method)
-				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
-				_arg_update_method="$2"
-				shift
-				;;
-			--update-method=*)
-				_arg_update_method="${_key##--update-method=}"
-				;;
-			-m*)
-				_arg_update_method="${_key##-m}"
-				;;
-			-i|--ip-mode)
-				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
-				_arg_ip_mode="$2"
-				shift
-				;;
-			--ip-mode=*)
-				_arg_ip_mode="${_key##--ip-mode=}"
-				;;
-			-i*)
-				_arg_ip_mode="${_key##-i}"
-				;;
-			-d|--domain)
-				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
-				_arg_domain="$2"
-				shift
-				;;
-			--domain=*)
-				_arg_domain="${_key##--domain=}"
-				;;
-			-d*)
-				_arg_domain="${_key##-d}"
-				;;
-			-s|--service-provider)
-				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
-				_arg_service_provider="$2"
-				shift
-				;;
-			--service-provider=*)
-				_arg_service_provider="${_key##--service-provider=}"
-				;;
-			-s*)
-				_arg_service_provider="${_key##-s}"
-				;;
-			-u|--username)
-				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
-				_arg_username="$2"
-				shift
-				;;
-			--username=*)
-				_arg_username="${_key##--username=}"
-				;;
-			-u*)
-				_arg_username="${_key##-u}"
-				;;
-			-p|--password)
-				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
-				_arg_password="$2"
-				shift
-				;;
-			--password=*)
-				_arg_password="${_key##--password=}"
-				;;
-			-p*)
-				_arg_password="${_key##-p}"
-				;;
-			-t|--token)
-				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
-				_arg_token="$2"
-				shift
-				;;
-			--token=*)
-				_arg_token="${_key##--token=}"
-				;;
-			-t*)
-				_arg_token="${_key##-t}"
-				;;
-			--interval)
-				test $# -lt 2 && die "Missing value for the optional argument '$_key'." 1
-				_arg_interval="$2"
-				shift
-				;;
-			--interval=*)
-				_arg_interval="${_key##--interval=}"
-				;;
-			-h|--help)
-				print_help
-				exit 0
-				;;
-			-h*)
-				print_help
-				exit 0
-				;;
-			*)
-				_PRINT_HELP=yes die "FATAL ERROR: Got an unexpected argument '$1'" 1
-				;;
-		esac
-		shift
-	done
-}
-
-parse_commandline "$@"
-
-# OTHER STUFF GENERATED BY Argbash
-
-### END OF CODE GENERATED BY Argbash (sortof) ### ])
-# [ <-- needed because of Argbash
-
-# The generated argbash help message does not look as nice as this:
-_help_message="$(cat << 'EOF'
-dynb - dynamic DNS update script for bash
-
-Usage
-=====
-dynb [options]
-
--h, --help                                displays this help message
---version                                 outputs the client version
---link                                    links to your script at ~/.local/bin/dynb
---reset                                   deletes the client blocking status file
-
-Configuration options
----------------------
--i | --ip-mode [ 4 | 6 | dual ]           updates type A (IPv4) and AAAA (IPv6) records
--m | --update-method [dyndns | domrobot]  choose if you want to use DynDNS2 or the DomRobot RPC-API
--s | --service-provider inwx              set your provider in case you are using DynDNS2
--d | --domain "dyndns.example.com"        set the domain you want to update
--u | --username "user42"                  depends on your selected update method and your provider
--p | --password "SuperSecretPassword"     depends on your selected update method and your provider
--t | --token "YourProviderGivenToken"     depends on your selected update method and your provider
-
-##### examples #####
-dynb --ip-mode dual --update-method domrobot --domain dyndns.example.com --username user42 --password SuperSecretPassword
-dynb --ip-mode dual --update-method dyndns --service-provider inwx --domain dyndns.example.com --username user42 --password SuperSecretPassword
-EOF
-)"
-
 function loopMode() {
   if [[ $_loopMode -eq 1 ]]; then
     return 0
@@ -345,42 +89,55 @@ function debugMode() {
   fi
 }
 
+function infoMessage() {
+  echo "$(logtime) INFO: $*"
+}
+
 function debugMessage() {
   if debugMode; then
-    echo "Debug: $*"
+    echo "$(logtime) DEBUG: $*"
   fi
 }
 
-function echoerr() { printf "%s\n" "$*" >&2; }
+function errorMessage() { printf "$(logtime) ERROR: %s\n" "$*" >&2; }
+
+function logtime() {
+  LOGTIME=$(date "+%Y-%m-%d %H:%M:%S")
+  echo "[$LOGTIME]"
+}
 
 # The main domain as an identifier for the dns zone is required for the updateRecord call
 function getMainDomain() {
-  request=$( echo "{}" | \
+  request=$(
-      jq '(.method="nameserver.list")' | \
+    echo "{}" |
-      jq "(.params.user=\"$DYNB_USERNAME\")" | \
+      jq '(.method="nameserver.list")' |
+      jq "(.params.user=\"$DYNB_USERNAME\")" |
       jq "(.params.pass=\"$DYNB_PASSWORD\")"
   )
 
-  _response=$(curl --silent  \
+  _response=$(
+    curl --silent \
       "$_interface_str" \
       --user-agent "$_userAgent" \
       --header "Content-Type: application/json" \
       --request POST $_INWX_JSON_API_URL \
       --data "$request" | jq ".resData.domains[] | select(inside(.domain=\"$DYNB_DYN_DOMAIN\"))"
   )
-  _main_domain=$( echo "$_response" | jq --raw-output '.domain'  )
+  _main_domain=$(echo "$_response" | jq --raw-output '.domain')
 }
 
 function fetchDNSRecords() {
-  request=$( echo "{}" | \
+  request=$(
-      jq '(.method="'nameserver.info'")' | \
+    echo "{}" |
-      jq "(.params.user=\"$DYNB_USERNAME\")" | \
+      jq '(.method="'nameserver.info'")' |
-      jq "(.params.pass=\"$DYNB_PASSWORD\")" | \
+      jq "(.params.user=\"$DYNB_USERNAME\")" |
-      jq "(.params.domain=\"$_main_domain\")" | \
+      jq "(.params.pass=\"$DYNB_PASSWORD\")" |
+      jq "(.params.domain=\"$_main_domain\")" |
       jq "(.params.name=\"$DYNB_DYN_DOMAIN\")"
   )
 
-  _response=$( curl --silent  \
+  _response=$(
+    curl --silent \
       "$_interface_str" \
       --user-agent "$_userAgent" \
       --header "Content-Type: application/json" \
@@ -388,7 +145,7 @@ function fetchDNSRecords() {
       --data "$request"
   )
 
-  _dns_records=$( echo "$_response" | jq '.resData.record[]' )
+  _dns_records=$(echo "$_response" | jq '.resData.record[]')
 }
 
 # requires parameter A or AAAA
@@ -408,8 +165,18 @@ function getDNSIP() {
 # 2. param: IP check server address
 # result to stdout
 function getRemoteIP() {
+  if [[ -n $_DNS_checkServer ]]; then
     curl --silent "$_interface_str" --user-agent "$_userAgent" \
-    --ipv"${1}" --dns-servers 1.1.1.1 --location "${2}"
+      --ipv"${1}" --dns-servers "$_DNS_checkServer" --location "${2}"
+  else
+    curl --silent "$_interface_str" --user-agent "$_userAgent" \
+      --ipv"${1}" --location "${2}"
+  fi
+  # shellcheck disable=2181
+  if [[ $? -gt 0 ]]; then
+    errorMessage "IPCheck (getRemoteIP ${1}) request failed"
+    exit 1
+  fi
 }
 
 # requires parameter
@@ -424,16 +191,18 @@ function updateRecord() {
     IP=$_new_IPv6
   fi
   if [[ $IP != "" ]]; then
-  request=$( echo "{}" | \
+    request=$(
-      jq '(.method="nameserver.updateRecord")' | \
+      echo "{}" |
-      jq "(.params.user=\"$DYNB_USERNAME\")" | \
+        jq '(.method="nameserver.updateRecord")' |
-      jq "(.params.pass=\"$DYNB_PASSWORD\")" | \
+        jq "(.params.user=\"$DYNB_USERNAME\")" |
-      jq "(.params.id=\"$ID\")" | \
+        jq "(.params.pass=\"$DYNB_PASSWORD\")" |
-      jq "(.params.content=\"$IP\")" | \
+        jq "(.params.id=\"$ID\")" |
+        jq "(.params.content=\"$IP\")" |
         jq "(.params.ttl=\"$TTL\")"
     )
 
-  _response=$(curl --silent  \
+    _response=$(
+      curl --silent \
         "$_interface_str" \
         --user-agent "$_userAgent" \
         --header "Content-Type: application/json" \
@@ -456,24 +225,24 @@ function dynupdate() {
   DYNV6_DYNDNS_UPDATE_URL="https://dynv6.com/api/update?zone=$DYNB_DYN_DOMAIN&token=$DYNB_TOKEN&"
 
   case $DYNB_SERVICE_PROVIDER in
-    inwx* | INWX* )
+    inwx* | INWX*)
       dyndns_update_url=$INWX_DYNDNS_UPDATE_URL
       ;;
-    deSEC* | desec* | dedyn* )
+    deSEC* | desec* | dedyn*)
       dyndns_update_url="${DESEC_DYNDNS_UPDATE_URL}"
       ;;
-    dynv6* )
+    dynv6*)
       dyndns_update_url="${DYNV6_DYNDNS_UPDATE_URL}"
       myip_str=ipv4
       myipv6_str=ipv6
       ;;
-    DuckDNS* | duckdns* )
+    DuckDNS* | duckdns*)
       dyndns_update_url="${DUCKDNS_DYNDNS_UPDATE_URL}"
       myip_str=ipv4
       myipv6_str=ipv6
       ;;
-    * )
+    *)
-    echoerr "$DYNB_SERVICE_PROVIDER is not supported"
+      errorMessage "$DYNB_SERVICE_PROVIDER is not supported"
       exit 1
       ;;
   esac
@@ -492,21 +261,22 @@ function dynupdate() {
 
   ## request ##
   case $DYNB_SERVICE_PROVIDER in
-    inwx* | INWX* )
+    inwx* | INWX*)
       _response=$(curl --silent "$_interface_str" \
         --user-agent "$_userAgent" \
         --user "$DYNB_USERNAME":"$DYNB_PASSWORD" \
-      "${dyndns_update_url}" )
+        "${dyndns_update_url}")
       ;;
-    deSEC* | desec* | dedyn* )
+    deSEC* | desec* | dedyn*)
       _response=$(curl --silent "$_interface_str" \
         --user-agent "$_userAgent" \
         --header "Authorization: Token $DYNB_TOKEN" \
         --get --data-urlencode "hostname=$DYNB_DYN_DOMAIN" \
-      "${dyndns_update_url}" )
+        "${dyndns_update_url}")
       ;;
-    dynv6* | duckDNS* | duckdns* )
+    dynv6* | duckDNS* | duckdns*)
-      _response=$(curl --silent "$_interface_str" \
+      _response=$(
+        curl --silent "$_interface_str" \
           --user-agent "$_userAgent" \
           "${dyndns_update_url}"
       )
@@ -514,66 +284,66 @@ function dynupdate() {
   esac
 
   case $_response in
-    good* | OK* | "addresses updated" )
+    good* | OK* | "addresses updated")
       if [[ $_response == "good 127.0.0.1" ]]; then
-        echoerr "Error: $_response: Request ignored."
+        errorMessage "$_response: Request ignored."
         return 1
       else
-        echo "$_response: The DynDNS update has been executed."
+        infoMessage "$_response: The DynDNS update has been executed."
         _errorCounter=0
         return 0
       fi
       ;;
-    nochg* )
+    nochg*)
-      echo "$_response: Nothing has changed, IP addresses are still up to date."
+      infoMessage "$_response: Nothing has changed, IP addresses are still up to date."
       return 1
       ;;
-    abuse )
+    abuse)
-      echoerr "Error: $_response: Username is blocked due to abuse."
+      errorMessage "$_response: Username is blocked due to abuse."
       return 1
       ;;
-    badauth | 401 )
+    badauth | 401)
-      echoerr "Error: $_response: Invalid username password combination."
+      errorMessage "$_response: Invalid username password combination."
       return 1
       ;;
-    badagent )
+    badagent)
-      echoerr "Error: $_response: Client disabled. Something is very wrong!"
+      errorMessage "$_response: Client disabled. Something is very wrong!"
       return 1
       ;;
-    !donator )
+    !donator)
-      echoerr "Error: $_response: An update request was sent, including a feature that is not available to that particular user such as offline options."
+      errorMessage "$_response: An update request was sent, including a feature that is not available to that particular user such as offline options."
       return 1
       ;;
-    !yours )
+    !yours)
-      echoerr "Error: $_response: The domain does not belong to your user account"
+      errorMessage "$_response: The domain does not belong to your user account"
       return 1
       ;;
-    notfqdn )
+    notfqdn)
-      echoerr "Error: $_response: Hostname $DYNB_DYN_DOMAIN is invalid"
+      errorMessage "$_response: Hostname $DYNB_DYN_DOMAIN is invalid"
       return 1
       ;;
-    nohost )
+    nohost)
-      echoerr "Error: $_response: Hostname supplied does not exist under specified account, enter new login credentials before performing an additional request."
+      errorMessage "$_response: Hostname supplied does not exist under specified account, enter new login credentials before performing an additional request."
       return 1
       ;;
-    numhost )
+    numhost)
-      echoerr "Error: $_response: Too many hostnames have been specified for this update"
+      errorMessage "$_response: Too many hostnames have been specified for this update"
       return 1
       ;;
-    dnserr )
+    dnserr)
-      echoerr "Error: $_response: There is an internal error in the dyndns update system. Retry update no sooner than 30 minutes."
+      errorMessage "$_response: There is an internal error in the dyndns update system. Retry update no sooner than 30 minutes."
       return 1
       ;;
-    911 | 5* )
+    911 | 5*)
-      echoerr "Error: $_response: A fatal error on provider side such as a database outage. Retry update no sooner than 30 minutes."
+      errorMessage "$_response: A fatal error on provider side such as a database outage. Retry update no sooner than 30 minutes."
       return 1
       ;;
-    * )
+    *)
       if [[ "$_response" == "$_status" ]]; then
-        echoerr "Error: An unknown response code has been received. $_response"
+        errorMessage "An unknown response code has been received. $_response"
         return 1
       else
-        echoerr "Error: unknown respnse code: $_response"
+        errorMessage "unknown respnse code: $_response"
         return 0
       fi
       ;;
@@ -581,68 +351,68 @@ function dynupdate() {
 }
 
 function setStatus() {
-  echo "_status=$1; _eventTime=$2; _errorCounter=$3; _statusHostname=$4; _statusUsername=$5; _statusPassword=$6" > /tmp/dynb.status
+  echo "_status=$1; _eventTime=$2; _errorCounter=$3; _statusHostname=$4; _statusUsername=$5; _statusPassword=$6" >/tmp/dynb.status
 }
 
 # handle errors from past update requests
 function checkStatus() {
   case $_status in
-    nochg* )
+    nochg*)
       if [[ _errorCounter -gt 1 ]]; then
-        echoerr "Error: The update client was spamming unnecessary update requests, something might be wrong with your IP-Check site."
+        errorMessage "The update client was spamming unnecessary update requests, something might be wrong with your IP-Check site."
-        echoerr "Fix your config an then delete $_statusFile"
+        errorMessage "Fix your config an then delete $_statusFile or restart your docker container"
         return 1
       fi
       ;;
-    nohost | !yours )
+    nohost | !yours)
-      if [[ "$_statusHostname" == "$DYNB_DYN_DOMAIN" && ( "$_statusUsername" == "$DYNB_USERNAME" || $_statusUsername == "$DYNB_TOKEN" ) ]]; then
+      if [[ "$_statusHostname" == "$DYNB_DYN_DOMAIN" && ("$_statusUsername" == "$DYNB_USERNAME" || $_statusUsername == "$DYNB_TOKEN") ]]; then
-        echoerr "Error: Hostname supplied does not exist under specified account, enter new login credentials before performing an additional request."
+        errorMessage "Hostname supplied does not exist under specified account, enter new login credentials before performing an additional request."
         return 1
       else
         rm "$_statusFile"
       fi
       return 0
       ;;
-    badauth | 401 )
+    badauth | 401)
       if [[ "$_statusUsername" == "$DYNB_USERNAME" && "$_statusPassword" == "$DYNB_PASSWORD" ]]; then
-        echoerr "Error: Invalid username password combination."
+        errorMessage "Invalid username password combination."
         return 1
       else
         rm "$_statusFile"
       fi
       return 0
       ;;
-    badagent )
+    badagent)
-      echoerr "Error: Client is deactivated by provider."
+      errorMessage "Client is deactivated by provider."
       echo "Fix your config and then manually remove $_statusFile to reset the client blockade."
       echo "If it still fails file an issue at github or try another client :)"
       return 1
       ;;
-    !donator )
+    !donator)
-      echoerr "Error: An update request was sent, including a feature that is not available to that particular user such as offline options."
+      errorMessage "An update request was sent, including a feature that is not available to that particular user such as offline options."
       echo "Fix your config and then manually remove $_statusFile to reset the client blockade"
       echo "If it still fails file an issue at github or try another client :)"
       return 1
       ;;
-    abuse )
+    abuse)
-      echoerr "Error: Username is blocked due to abuse."
+      errorMessage "Username is blocked due to abuse."
       echo "Fix your config and then manually remove $_statusFile to reset the client blockade"
       echo "If it still fails file an issue at github or try another client :)"
       return 1
       ;;
-    911 | 5* )
+    911 | 5*)
-      delta=$(( $(date +%s) - _eventTime ))
+      delta=$(($(date +%s) - _eventTime))
       if [[ $delta -lt 1800 ]]; then
-        echoerr "$_status: The provider currently has an fatal error. DynB will wait for next update until 30 minutes have passed since last request, $(date --date=@$delta -u +%M) minutes already passed."
+        errorMessage "$_status: The provider currently has an fatal error. DynB will wait for next update until 30 minutes have passed since last request, $(date --date=@$delta -u +%M) minutes already passed."
         return 1
       else
         rm "$_statusFile"
       fi
       return 0
       ;;
-    * )
+    *)
       if [[ _errorCounter -gt 1 ]]; then
-        echoerr "Error: An unknown response code has repeatedly been received. $_response"
+        errorMessage "An unknown response code has repeatedly been received. $_response"
         return 1
       else
         return 0
@@ -654,30 +424,48 @@ function checkStatus() {
 # requires parameter
 # 1. param: 4 or 6 for IP version
 function ipHasChanged() {
-  if [[ ${1} == 4 ]]; then
+  case ${1} in
+    4)
       remote_ip=$(getRemoteIP 4 $_ipv4_checker)
       if [[ $DYNB_UPDATE_METHOD == domrobot ]]; then
         dns_ip=$(getDNSIP A)
       else
-      dns_ip=$(dig @${_DNS_checkServer} in a +short "$DYNB_DYN_DOMAIN")
+        if [[ -n $_DNS_checkServer ]]; then
+          dig_response=$(dig @"${_DNS_checkServer}" in a +short "$DYNB_DYN_DOMAIN")
+        else
+          dig_response=$(dig in a +short "$DYNB_DYN_DOMAIN")
         fi
+        if [[ $dig_response == ";; connection timed out; no servers could be reached" ]]; then
+          errorMessage "DNS request failed $dig_response"
+          return 0
         fi
-  if [[ ${1} == 6 ]]; then
+        dns_ip=$dig_response
+      fi
+      _new_IPv4=$remote_ip
+      debugMessage "New IPv4: $_new_IPv4 old was: $dns_ip"
+      ;;
+    6)
       remote_ip=$(getRemoteIP 6 $_ipv6_checker)
       if [[ $DYNB_UPDATE_METHOD == domrobot ]]; then
         dns_ip=$(getDNSIP AAAA)
       else
-      dns_ip=$(dig @${_DNS_checkServer} in aaaa +short "$DYNB_DYN_DOMAIN")
+        if [[ -n $_DNS_checkServer ]]; then
-    fi
+          dig_response=$(dig @"${_DNS_checkServer}" in aaaa +short "$DYNB_DYN_DOMAIN")
-  fi
-
-  if [[ ${1} == 4 ]]; then
-    _new_IPv4=$remote_ip
-    debugMessage "New IPv4: $_new_IPv4 old was: $dns_ip"
         else
+          dig_response=$(dig in aaaa +short "$DYNB_DYN_DOMAIN")
+        fi
+        if [[ $dig_response == ";; connection timed out; no servers could be reached" ]]; then
+          errorMessage "DNS request failed $dig_response"
+          return 0
+        fi
+        dns_ip=$dig_response
+      fi
       _new_IPv6=$remote_ip
       debugMessage "New IPv6: $_new_IPv6 old was: $dns_ip"
-  fi
+      ;;
+    *) ;;
+
+  esac
 
   if [[ "$remote_ip" == "$dns_ip" ]]; then
     return 0
@@ -691,42 +479,54 @@ function ipHasChanged() {
 ################
 
 function handleParameters() {
+  # shellcheck disable=SC2154
   if [[ $_arg_version == "on" ]]; then
     echo $_version
     exit 0
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_link == "on" ]]; then
     ln --verbose --symbolic "$(realpath "$0")" "$HOME/.local/bin/dynb"
     exit 0
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_reset == "on" ]]; then
     rm --verbose "$_statusFile"
     exit 0
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_debug == "on" ]]; then
     _debug=1
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_update_method != "" ]]; then
     DYNB_UPDATE_METHOD=$_arg_update_method
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_ip_mode != "" ]]; then
     DYNB_IP_MODE=$_arg_ip_mode
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_domain != "" ]]; then
     DYNB_DYN_DOMAIN=$_arg_domain
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_service_provider != "" ]]; then
     DYNB_SERVICE_PROVIDER=$_arg_service_provider
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_username != "" ]]; then
     DYNB_USERNAME=$_arg_username
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_password != "" ]]; then
     DYNB_PASSWORD=$_arg_password
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_token != "" ]]; then
     DYNB_TOKEN=$_arg_token
   fi
+  # shellcheck disable=SC2154
   if [[ $_arg_interval != "" ]]; then
     DYNB_INTERVAL=$_arg_interval
   fi
@@ -757,6 +557,17 @@ function handleParameters() {
   if [[ $DYNB_DEBUG == true ]]; then
     _debug=1
   fi
+  # shellcheck disable=SC2154
+  if [[ -n $DYNB_IPv4_CHECK_SITE ]]; then
+    _ipv4_checker=$DYNB_IPv4_CHECK_SITE
+  fi
+  # shellcheck disable=SC2154
+  if [[ -n $DYNB_IPv6_CHECK_SITE ]]; then
+    _ipv6_checker=$DYNB_IPv6_CHECK_SITE
+  fi
+  if [[ -n $DYNB_DNS_CHECK_SERVER ]]; then
+    _DNS_checkServer=$DYNB_DNS_CHECK_SERVER
+  fi
   return 0
 }
 
@@ -765,30 +576,31 @@ function handleParameters() {
 ##################
 
 function checkDependencies() {
-  ## If there will be more general dependencies use a loop
+  failCounter=0
-  # for i in curl and some other stuff; do
+  for i in curl dig; do
-  #   if ! command -v $i >/dev/null 2>&1; then
+    if ! command -v $i >/dev/null 2>&1; then
-  #     echoerr "Error: could not find \"$i\", DynB depends on it. "
+      errorMessage "could not find \"$i\", DynB depends on it. "
-  #     exit 1
+      ((failCounter++))
-  #   fi
+    fi
-  # done
+  done
-  [[ -x $(command -v jq 2> /dev/null) ]] || {
+  [[ -x $(command -v jq 2>/dev/null) ]] || {
     if [[ $DYNB_UPDATE_METHOD != dyndns* ]]; then
       echo "This script depends on jq and it is not available." >&2
-      exit 1
+      ((failCounter++))
     fi
   }
+  if [[ failCounter -gt 0 ]]; then
+    exit 1
+  fi
 }
 
 function doUnsets() {
   unset _network_interface
   unset _DNS_checkServer
   unset _dns_records
-  unset DYNB_DYN_DOMAIN
   unset _has_getopt
   unset _help_message
   unset _INWX_JSON_API_URL
-  unset DYNB_IP_MODE
   unset _ipv4_checker
   unset _ipv6_checker
   unset _is_IPv4_enabled
@@ -796,14 +608,21 @@ function doUnsets() {
   unset _main_domain
   unset _new_IPv4
   unset _new_IPv6
-  unset DYNB_PASSWORD
-  unset DYNB_USERNAME
-  unset DYNB_SERVICE_PROVIDER
   unset _version
+  unset DYNB_DYN_DOMAIN
+  unset DYNB_USERNAME
+  unset DYNB_PASSWORD
+  unset DYNB_TOKEN
+  unset DYNB_SERVICE_PROVIDER
+  unset DYNB_IP_MODE
+  unset DYNB_INTERVAL
+  unset DYNB_IPv4_CHECK_SITE
+  unset DYNB_IPv6_CHECK_SITE
+  unset DYNB_DNS_CHECK_SERVER
+  unset DYNB_DEBUG
 }
 
-function doUpdates() {
+function doDomrobotUpdates() {
-  if [[ $DYNB_UPDATE_METHOD == "domrobot" ]]; then
   getMainDomain
   fetchDNSRecords
   if [[ $_is_IPv4_enabled == true ]]; then
@@ -822,17 +641,17 @@ function doUpdates() {
       debugMessage "Skip IPv6 record update, it is already up to date"
     fi
   fi
-  fi
+}
 
-  if [[ $DYNB_UPDATE_METHOD == "dyndns" ]]; then
+function doDynDNS2Updates() {
   changed=0
   if [[ $_is_IPv4_enabled == true ]]; then
     ipHasChanged 4
-      (( changed += $? ))
+    ((changed += $?))
   fi
   if [[ $_is_IPv6_enabled == true ]]; then
     ipHasChanged 6
-      (( changed += $? ))
+    ((changed += $?))
   fi
   if [[ $changed -gt 0 ]]; then
     if checkStatus; then
@@ -841,14 +660,23 @@ function doUpdates() {
         debugMessage "DynDNS2 update success"
       else
         debugMessage "Save new status after dynupdate has failed"
-          setStatus "$_response" "$(date +%s)" $(( _errorCounter += 1 )) "$DYNB_DYN_DOMAIN" "${DYNB_USERNAME}" "${DYNB_PASSWORD}${DYNB_TOKEN}"
+        setStatus "$_response" "$(date +%s)" $((_errorCounter += 1)) "$DYNB_DYN_DOMAIN" "${DYNB_USERNAME}" "${DYNB_PASSWORD}${DYNB_TOKEN}"
       fi
     else
       debugMessage "Skip DynDNS2 update, checkStatus fetched previous error."
     fi
   else
-      debugMessage "Skip DynDNS2 update, IPs are up to date"
+    debugMessage "Skip DynDNS2 update, IPs are up to date or there is a connection problem"
   fi
+}
+
+function doUpdates() {
+  if [[ $DYNB_UPDATE_METHOD == "domrobot" ]]; then
+    doDomrobotUpdates
+  fi
+
+  if [[ $DYNB_UPDATE_METHOD == "dyndns" ]]; then
+    doDynDNS2Updates
   fi
 }
 
@@ -856,8 +684,8 @@ function doUpdates() {
 ## MAIN method ##
 #################
 function dynb() {
-  ## parameters and checks
+  # shellcheck disable=SC1091,SC1090
-  checkDependencies
+  source "$(dirname "$(realpath "$0")")/dynb-parsing.sh"
 
   # shellcheck source=.env
   if test -f "$_configFile"; then
@@ -876,14 +704,12 @@ function dynb() {
     source "$_statusFile"
   fi
 
+  ## parameters and checks
   handleParameters
-
+  checkDependencies
-  ## execute operations
-
 
   if loopMode; then
-    while checkStatus
+    while :; do
-    do
       doUpdates
       sleep $DYNB_INTERVAL
     done
@@ -898,7 +724,7 @@ function dynb() {
 ## END MAIN section ##
 ######################
 
-  dynb "${@}"
+dynb "${@}"
-  exit $?
+exit $?
 
 # ] <-- needed because of Argbash