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landing/docs/Bash-Scripts/011-bash-loops.md

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+# Loops
+
+Loops are fundamental for automation. Bash provides `for`, `while`, and `until` loops to repeat commands efficiently.
+
+---
+
+### For Loops
+
+The `for` loop iterates through a list of items.
+
+```bash
+for var in ${list}
+do
+    your_commands
+done
+```
+
+Example: Loop through a list of users.
+
+```bash
+touch for_users.sh
+```
+
+Open `for_users.sh` and add:
+
+```bash
+#!/usr/bin/env bash
+
+users="Dev Team Six softwareshinobi troy"
+
+for user in ${users}
+do
+    echo "${user}"
+done
+```
+
+Save and exit. Make it executable and run:
+
+```bash
+chmod +x for_users.sh
+./for_users.sh
+```
+
+Output:
+```
+Dev Team Six
+softwareshinobi
+troy
+```
+
+Loop through a range of numbers:
+
+```bash
+touch for_numbers.sh
+```
+
+Open `for_numbers.sh` and add:
+
+```bash
+#!/usr/bin/env bash
+
+for num in {1..10}
+do
+    echo ${num}
+done
+```
+
+Save, make executable, and run.
+
+### While Loops
+
+A `while` loop continues as long as its condition remains true.
+
+```bash
+while [[ your_condition ]]
+do
+    your_commands
+done
+```
+
+Example: Counter from 1 to 10.
+
+```bash
+touch while_counter.sh
+```
+
+Open `while_counter.sh` and add:
+
+```bash
+#!/usr/bin/env bash
+
+counter=1
+while [[ $counter -le 10 ]]
+do
+    echo $counter
+    ((counter++)) # Increment counter
+done
+```
+
+Save, make executable, run.
+
+Example: Require user input. Loop until a non-empty name is provided.
+
+```bash
+touch while_input.sh
+```
+
+Open `while_input.sh` and add:
+
+```bash
+#!/usr/bin/env bash
+
+read -p "What is your name? " name
+
+while [[ -z "${name}" ]]
+do
+    echo "Name cannot be blank. Please enter a valid name!"
+    read -p "Enter your name again: " name
+done
+
+echo "Hi there ${name}!"
+```
+
+Save, make executable, run (test with empty and valid input).
+
+### Until Loops
+
+An `until` loop runs *until* its condition becomes true.
+
+```bash
+until [[ your_condition ]]
+do
+    your_commands
+done
+```
+
+Example: Counter from 1 to 10.
+
+```bash
+touch until_loop.sh
+```
+
+Open `until_loop.sh` and add:
+
+```bash
+#!/usr/bin/env bash
+
+count=1
+until [[ $count -gt 10 ]]
+do
+    echo $count
+    ((count++))
+done
+```
+
+Save, make executable, run.
+
+### Continue and Break
+
+Control loop flow with `continue` (skip current iteration) and `break` (exit loop entirely).
+
+#### `continue`
+
+```bash
+touch continue_example.sh
+```
+
+Open `continue_example.sh` and add:
+
+```bash
+#!/usr/bin/env bash
+
+for i in 1 2 3 4 5
+do
+    if [[ $i -eq 2 ]]; then
+        echo "Skipping number 2"
+        continue # Skip to next iteration
+    fi
+    echo "i is equal to $i"
+done
+```
+
+Save, make executable, run.
+
+#### `break`
+
+```bash
+touch break_example.sh
+```
+
+Open `break_example.sh` and add:
+
+```bash
+#!/usr/bin/env bash
+
+num=1
+while [[ $num -lt 10 ]]; do
+    if [[ $num -eq 5 ]]; then
+        break # Exit loop
+    fi
+    ((num++))
+done
+echo "Loop completed. Num stopped at: $num"
+```
+
+Save, make executable, run.
+
+For nested loops, `break N` exits `N` levels of loops. `break 2` exits the current and the parent loop.
+
+```bash
+touch nested_break_example.sh
+```
+
+Open `nested_break_example.sh` and add:
+
+```bash
+#!/usr/bin/env bash
+
+for (( a = 1; a < 3; a++ )); do # Outer loop
+    echo "Outer loop: $a"
+    for (( b = 1; b < 5; b++ )); do # Inner loop
+        if [[ $b -gt 2 ]]; then
+            echo "  Breaking inner and outer loop at b=$b"
+            break 2 # Exits both loops
+        fi
+        echo "  Inner loop: $b"
+    done
+done
+echo "All loops finished."
+```
+
+Save, make executable, run.