diff --git a/readme.md b/readme.md
index a73f590..2043313 100644
--- a/readme.md
+++ b/readme.md
@@ -22,16 +22,24 @@ For most API calls it is necessary to provide login information. There are two w
 - the default location is `~/.inwx-conf.json`
 - a minial configuration file for specifying the credentials would look as follows: 
 
-	{
-		"account": {
-			"username": "___",
-			"password": "___"
-		}
-	}
+```
+{
+    "account": {
+        "username": "___",
+        "password": "___"
+    }
+}
+```
 
 
 ## Commands
 
+### `info`
+
+- synopsis: `inwx info`
+- description: for listing the records of a domain
+
+
 ### `list`
 
 - synopsis: `inwx list <domain>`
@@ -44,3 +52,9 @@ For most API calls it is necessary to provide login information. There are two w
 - description: for creating or updating a records of a domain
 - example: `inwx save example.org dat TXT 'foo bar'`
 
+
+### `certbot-hook`
+
+- synopsis: `inwx certbot-hook`
+- description: for executing the DNS certbot challenge; will read the environment variables `CERTBOT_DOMAIN` and `CERTBOT_VALIDATION` to store a `TXT` record
+
diff --git a/source/head.py b/source/head.py
index 23fa5a0..5212350 100644
--- a/source/head.py
+++ b/source/head.py
@@ -8,5 +8,5 @@ import json as _json
 import http.client as _http_client
 import argparse as _argparse
 import pathlib as _pathlib
-
+import time as _time
 
diff --git a/source/main.py b/source/main.py
index 87f135e..ff50521 100644
--- a/source/main.py
+++ b/source/main.py
@@ -5,40 +5,77 @@ def args(
 		description = "INWX CLI Frontend"
 	)
 	argumentparser.add_argument(
-		'--conf',
+		"-c",
+		"--conf",
 		dest = "conf",
-		default = _os.path.join(str(_pathlib.Path.home()), ".inwx-conf.json")
+		default = _os.path.join(str(_pathlib.Path.home()), ".inwx-conf.json"),
+		metavar = "<conf>",
+		help = "path to configuration file",
 	)
 	argumentparser.add_argument(
-		'--environment',
+		"-e",
+		"--environment",
 		dest = "environment",
-		default = None
+		metavar = "<environment>",
+		default = None,
+		help = "environment to use; one of the keys in the 'url' filed of the configuration; overwrites the configuration value",
 	)
 	argumentparser.add_argument(
-		'--username',
+		"-u",
+		"--username",
 		dest = "username",
-		default = None
+		metavar = "<username>",
+		default = None,
+		help = "username; overwrites the configuration value",
 	)
 	argumentparser.add_argument(
-		'--password',
+		"-p",
+		"--password",
 		dest = "password",
-		default = None
+		metavar = "<password>",
+		default = None,
+		help = "password; overwrites the configuration value",
 	)
 	'''
 	argumentparser.add_argument(
-		'--domain',
+		"-d",
+		"--domain",
 		dest = "domain",
-		default = None
+		default = None,
+		metavar = "<domain>",
+		help = "the domain to work with"
 	)
 	'''
 	argumentparser.add_argument(
-		"command",
-		type = str
+		"-x",
+		"--challenge-prefix",
+		dest = "challenge_prefix",
+		metavar = "<challenge-prefix>",
+		default = "_acme-challenge",
+		help = "which subdomain to use for ACME challanges",
+	)
+	argumentparser.add_argument(
+		"-w",
+		"--delay",
+		dest = "delay",
+		type = float,
+		default = 60.0,
+		metavar = "<delay>",
+		help = "seconds to wait at end of certbot auth hook",
+	)
+	argumentparser.add_argument(
+		"action",
+		type = str,
+		choices = ["info", "list", "save", "certbot-hook"],
+		metavar = "<action>",
+		help = "action to execute",
 	)
 	argumentparser.add_argument(
 		"parameter",
 		nargs = "*",
-		type = str
+		type = str,
+		metavar = "<parameters>",
+		help = "action specific parameters",
 	)
 	arguments = argumentparser.parse_args()
 	return arguments
@@ -53,14 +90,14 @@ def main(
 	if (not (arguments.username is None)): conf_set("account.username", arguments.username)
 	if (not (arguments.password is None)): conf_set("account.password", arguments.password)
 	
-	if (arguments.command == "info"):
+	if (arguments.action == "info"):
 		result = api_macro_info(
 			conf_get("environment"),
 			conf_get("account.username"),
 			conf_get("account.password")
 		)
 		print(_json.dumps(result, indent = "\t"))
-	elif (arguments.command == "list"):
+	elif (arguments.action == "list"):
 		domain = arguments.parameter[0]
 		result = api_macro_list(
 			conf_get("environment"),
@@ -69,7 +106,7 @@ def main(
 			domain
 		)
 		print(_json.dumps(result, indent = "\t"))
-	elif (arguments.command == "save"):
+	elif (arguments.action == "save"):
 		domain = arguments.parameter[0]
 		name = arguments.parameter[1]
 		type_ = arguments.parameter[2]
@@ -84,8 +121,25 @@ def main(
 			content
 		)
 		# print(_json.dumps(result, indent = "\t"))
+	elif (arguments.action == "certbot-hook"):
+		domain_full_parts = _os.environ["CERTBOT_DOMAIN"].split(".", 1)
+		domain = domain_full_parts[1]
+		name = (arguments.challenge_prefix + "." + domain_full_parts[0])
+		type_ = "TXT"
+		content = _os.environ["CERTBOT_VALIDATION"]
+		api_macro_save(
+			conf_get("environment"),
+			conf_get("account.username"),
+			conf_get("account.password"),
+			domain,
+			name,
+			type_,
+			content
+		)
+		_time.sleep(arguments.delay)
+		# print(_json.dumps(result, indent = "\t"))
 	else:
-		log("unhandled command '%s'" % (arguments.command, ))
+		log("unhandled action '%s'" % (arguments.action, ))
 	
 
 try: