end of day 5 week 1

week 1/day 5/exo3.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+read -p "Please enter your username: " username
+
+if [[ -z "$username" ]]; then
+    echo "You must enter a username"
+    exit 1
+fi
+
+badChar=false
+
+for ((i=0; i<${#username}; i++)); do
+    char="${username:i:1}"
+    if ! [[ "$char" =~ [A-Za-z] ]]; then
+        badChar=true
+        break
+    fi
+done
+
+firstChar="${username:0:1}"
+validFirstLetter=false
+
+if [[ "$firstChar" =~ [A-Za-z] ]]; then
+    validFirstLetter=true
+fi
+
+if ! $badChar && (( ${#username} <= 20 )) && $validFirstLetter; then
+    echo "The username $username is valid"
+else
+    echo "The username is not valid"
+fi