Added bash code to use a Telegram bot to notify you on dynamically changing IP address.

send_telegram_dynamic_ip.sh

@@ -0,0 +1,57 @@
+#!/bin/sh
+
+#################################################################
+# Script to send the IP address of a host to you using a 	#
+# Telegram bot. This script also adds a cron job, so that the	#
+# bot nofifies you with every boot.				#
+#                                                               #
+# Author:           Maximilian Stiefel                          #
+# Last modified:    26. April 2018                              #
+# CLI usage:        						#
+# Required PKGs:    mail 					#
+#                                                               #
+#################################################################
+
+#################################################################
+# Vars								#
+#################################################################
+HOST=$(hostname)
+FILE=`realpath $0`
+NU_PARAMS=2
+
+#################################################################
+# Action							#
+#################################################################
+# Check if the expected number of parameters is given.  
+if [ $# != $NU_PARAMS ]
+then
+	echo "Error: Illegal number of parameters."	
+	exit 1; 
+fi
+# Get bot token and chat id.
+BOT=$1
+CHAT_ID=$2
+URL="https://api.telegram.org/bot$BOT/sendMessage"
+ENTRY="@reboot  $FILE $BOT $CHAT_ID"
+# Wait until we are online.
+while ! wget -q --spider http://google.com ; do true; done
+# Get private IP.
+CURRENT_IP=$(ip addr | grep 'state UP' -A2 | tail -n1 | awk '{print $2}' | cut -f1  -d'/')
+SUBJECT="IP of $HOST: $CURRENT_IP"
+MESSAGE="Hej! Ha en trevlig dag. IP adressen du ville veta är $CURRENT_IP."
+# Instruct bot.
+curl -s -X POST $URL -d chat_id=$CHAT_ID -d text="$MESSAGE" > /dev/null
+echo "Message sent."
+# Grep returns zero if entry is found.
+if ! crontab -l | grep -q "$ENTRY" ; then
+	crontab -l > cron
+	echo "$ENTRY" >> cron
+	crontab cron
+	rm cron
+	echo "Added $ENTRY" 
+	echo "to crontab."
+else
+	echo "Crontab entry $ENTRY"
+	echo "already exists."
+fi
+exit 0;