adds new birthday ex

advanced/learning_bash_scripting.md

@@ -454,6 +454,34 @@ echo "or may I call you $first?"
 It is worth discovering what happens when you supply too many or to little values.
 Please try this out!
 
+# Coding challenge - Birthday **day**
+
+Write me `bash` program that asks for your date of birth and prints the day of the week that was.
+Like the output below.
+
+```
+waldek@server:~$ bash birthday.sh 
+what is your birthday (day month year)? 07 10 1986
+you where born on a Tuesday
+```
+
+<details>
+<summary>Spoiler warning!</summary>
+
+```bash
+#!/bin/bash
+
+read -p "what is your date of birth? (day month year) " day month year
+
+day_of_the_week=$(date +%A -d "$month/$day/$year")
+
+echo "you where born on a $day_of_the_week"
+```
+
+</details>
+
+
+
 ## With command line arguments
 
 We can create a similar behaviour but with command line arguments.