Add Bash elif tutorial

tutorials/learnshell.org/en/Welcome.md

@@ -20,6 +20,7 @@ Just click on the chapter you wish to begin from, and follow the instructions. G
 - [[Loops]]
 - [[Array-Comparison]]
 - [[Shell Functions]]
+- [[elif]]
 
 ### Advanced Tutorials
 

tutorials/learnshell.org/en/elif.md

@@ -0,0 +1,60 @@
+# Tutorial
+--------
+In Bash scripting, `elif` is used to handle multiple conditions in an `if` statement. It stands for "else if" and allows you to check additional conditions if the initial `if` condition is false. It's useful for branching  beyond just `if` and `else`.
+
+<b> Example: </b>
+
+```bash
+if [ $num -eq 1 ]; then
+    echo "One"
+elif [ $num -eq 2 ]; then
+    echo "Two"
+else
+    echo "Other"
+fi
+```
+
+# Exercise 
+In this exercise, you will need to use an `if`, `elif`, and `else` statement to evaluate the value of a variable called `color`.
+
+Your task is to:
+- Print `"You chose black!"` if the value of `color` is `"black"`
+- Print `"You chose green!"` if the value is `"green"`
+
+- Print `"You chose purple!"` if the value is `"purple"`
+- Print `"You chose orange!"` if the value is `"orange"`
+- Print `"Unknown/uncataloged color, please try again!"` for any other value
+
+Set `color="black"` to begin, and write the conditional logic that produces the correct output.
+
+# Tutorial Code
+```bash
+#!/bin/bash
+#enter your code here
+```
+# Expected Output
+You chose black!
+
+# Solution
+```bash
+#!/bin/bash
+
+color="black"
+
+if [ "$color" == "black" ]; then
+    echo "You chose black!"
+elif [ "$color" == "green" ]; then
+    echo "You chose green!"
+
+elif [ "$color" == "purple" ]; then
+    echo "You chose purple!"
+
+elif [ "$color" == "orange" ]; then
+    echo "You chose orange!"   
+
+else
+    echo "Unknown/uncataloged color, please try again!"
+fi
+```
+
+[[Welcome]]