content: improved bash scripting, minor improvements to advanced git and workflows

Author: debel

README.md

@@ -6,5 +6,7 @@ A short course about learning to use bash and git as a software developer.
 
 All content compiled and prepared by [Mihail Mikov](https://github.com/debel) with linked attributions within the text.
 
+All materials linked from primary sources, mainly: the [git docs](https://git-scm.com/docs), and the [Pro git book](https://git-scm.com/book)
+
 The theme is a port of the [Hugo Terminal Theme](https://github.com/panr/hugo-theme-terminal) created by [panr](https://github.com/panr). All design decisions, colour schemes, and visual aesthetics are credited to the original author. Astro port created by [Dennis Klappe](https://github.com/dennisklappe).
 

src/content/lessons/advanced-git-features.md

@@ -23,8 +23,8 @@ There are many ways to get to a commit.
 ```bash
 master^ # E (parent commit)
 master~3 # A (third ancestor)
-C^^ # A
-B~1 # A
+C^^ # A (parent of parent)
+B~1 # A (parent)
 ^B # everything except A and B
 ```
 
@@ -33,12 +33,12 @@ B~1 # A
 *parents* vs *ancestors*
 ![history with merge](https://git-scm.com/book/en/v2/images/basic-merging-2.png)
 ```bash
-master^ # C4 first parent of a merge commit
-master^2 # C5 second parent of a merge commit
+master^ # C4 -- first parent of a merge commit
+master^2 # C5 -- second parent of a merge commit
 
-iss53~2 # C2 second ancestor i.e. the parent of the parent
+iss53~2 # C2 -- second ancestor (the parent of the parent)
 
-master^2~1 # C3
+master^2~1 # C3 -- the parent of the second parent
 ```
 
 ---
@@ -77,7 +77,7 @@ HEAD@{5.days.ago}
 
 ## Blame
 
-`blame` allow us to understand when changes were made.
+`blame` allow us to understand who and when made changes.
 
 ```bash
 # display which commit last changed each line of my-file
@@ -139,7 +139,7 @@ The main difference between a Lightweight tag and a branch is that tags
 **CANNOT** be changed to point to a different commit. 
 
 ```bash
-# tag the current commit as v1
+# tag the current commit as v2
 git tag v2.0.0
 
 # tag a previous commit in the history
@@ -160,7 +160,7 @@ They can be signed (like commits). They **CANNOT** be moved as well.
 git tag -a v2.3.0 -m "Release v2.3: Blue Kiwi"
 
 # create a signed annotated tag
-git tag -a -s v2.5.0 -m "Notes fro version 2.5 
+git tag -a -s v2.5.0 -m "Notes for version 2.5"
 ```
 
 ---
@@ -213,7 +213,8 @@ git bisect bad
 # mark a commit as good i.e. not containing the bug
 git bisect good 25aef7
 
-# delete the bisect state and return to the initial starting commit
+# delete the bisect state and return
+# to the initial starting commit
 git bisect reset
 ```
 
@@ -222,19 +223,21 @@ git bisect reset
 Bisect will try to choose the minimum number of commits you need to review.
 
 You can use an appropriate command to automatically validate if the commit is good or bad.
-(e.g. compile the code, run tests, or performance benchmarks)
+(e.g. compile the code, run tests or performance benchmarks)
 
 ---
 
 ## Multiple work-trees
 
 Git allows you to have multiple versions checked-out at the same time:
 ```bash
-# creates a branch called bugfix and checks out into a working directory
-# called bugfix in the parent of the current directory
+# creates a branch called bugfix and checks it out
+# into a working directory called bugfix
+# in the parent of the current directory
 git workspace add ../bugfix
 
-# checkout branch origin/broken into a independent working directory
+# checkout branch origin/broken into a
+# separate working directory in your home directory
 git worktree add ~/my-project-bugfix origin/broken
 ```
 
@@ -245,7 +248,8 @@ git worktree add ~/my-project-bugfix origin/broken
 git worktree list
 
 # delete a worktree, needs to be clean
-# the corresponding branch is still part of the project history
+# the corresponding branch is still
+# part of the project history
 git worktree remove bugfix
 ```
 
@@ -277,7 +281,7 @@ but all files will be untracked.
 ### Use case: deploy branch
 
 After creating a disconnected (orphan) branch, you can
-delete or ignore all "regular" project files, leaving
+delete or ignore all "regular" project files, committing
 only your `output` / `build` directory.
 
 ---
@@ -328,7 +332,8 @@ but keep their histories separate.
 ---
 
 ```bash
-# add an existing repository as a submodule of the current repo
+# add an existing repository as a 
+# submodule of the current repo
 git submodule add path/to/other/repo
 
 # clone a repository including all submodules

src/content/lessons/bash-scripting.md

@@ -322,16 +322,34 @@ done
 myarray=(1 "A" 2 "B")
 
 # assign to an index in an array
-myarray[0]=5
+myarray[0]="hi"
 
 # print array element at index i
 echo ${myarray[i]}
+```
+
+---
 
+```bash
 # print length of array element at index i
 echo ${#myarray[i]}
 
 # print length of array itself
 echo ${#myarray[@]}
+
+# append items to an array
+myarray+=(7 "Z")
+```
+
+---
+
+Looping over each element of an array:
+
+```bash
+colors=("red" "green" "yellow")
+for color in "${colors[@]}"; do
+  echo "The traffic light is $color"
+done
 ```
 
 ---
@@ -341,7 +359,7 @@ echo ${#myarray[@]}
 There are special variable that allow you to handle script arguments.
 
 ```bash
-# print number of passed-in arguments
+# print number of arguments passed to the script
 echo "$#"
 
 # an array containing all arguments
@@ -371,6 +389,29 @@ my-script hello world
 
 ---
 
+## Prompting for user input
+
+Use the `read` command to block execution and allow the user to provide input through `stdin`:
+
+```bash
+# program stops and waits for the user to input a line of text
+read line
+echo "$line"
+```
+
+---
+
+If more than one variable is provided, the line will be split into words.
+
+The `-p` option allows for adding a prompt:
+
+```bash
+read -p "Full Name: " first last
+echo "My name is $last, $first $last"
+```
+
+---
+
 ## Handling signals
 
 Use the `trap` command to execute code as a response to a system signal:
@@ -450,6 +491,27 @@ myfunc() { echo "$1 $2 $3"; }
 
 ---
 
+## Doing math in bash
+
+By default everything in the console is treated as a string.
+Use the `$((<expression>))` syntax to perform math.
+
+```bash
+echo "1 + 1 = $((1+1))"
+# prints 1 + 1 = 2
+
+# a random number between 1 and 10
+echo "$((RANDOM % 10 + 1))"
+
+# by default $RANDOM will hold a random
+# number between 0 and 32767
+echo $RANDOM
+```
+
+> Inside a math expression variables should **NOT** start with an `$`
+
+---
+
 ## Linting with shellcheck
 
 Shellcheck is a powerful tool that can find many mistakes and problems in your scripts.
@@ -464,3 +526,104 @@ shellcheck my-script
 ---
 
 > **Fun fact:** there is a version of the popular containerization tool Docker [written entirely in bash](https://github.com/p8952/bocker)
+---
+
+<class-work>
+
+### Create a number guessing game
+
+1. Create a script called guess-num.sh
+2. Create a variable holding a random number between 0 and 100
+3. In a loop, allow the user to guess the number
+4. Alert the user if their guess was high or low
+5. Congratulate the user when they guess the number
+
+</class-work>
+
+<bonus-content>
+
+## Complex example: interactive menu
+
+The code below demonstrates a more complex script that displays an interactive menu
+which allows the user to choose options using the arrow keys.
+
+It uses arrays, variables, functions, loops, case conditionals and math.
+
+```bash
+#!/bin/bash
+
+# Menu items
+options=("Install Package" "Update System" "View Logs" "Configure Settings" "Exit")
+
+# Currently selected index
+selected=0
+
+# Function to draw the menu
+draw_menu() {
+  clear
+  echo "=== Main Menu ==="
+  echo "Use ↑/↓ arrows and Enter to select"
+  echo ""
+
+  for i in "${!options[@]}"; do
+    if [ $i -eq $selected ]; then
+      echo "→ ${options[$i]}" # Selected item
+    else
+      echo "  ${options[$i]}"
+    fi
+  done
+}
+
+# Function to read arrow keys
+read_input() {
+  read -rsn1 key
+  if [[ $key == $'\x1b' ]]; then
+    read -rsn2 key
+  fi
+  echo "$key"
+}
+
+# Main loop
+while true; do
+  draw_menu
+
+  key=$(read_input)
+
+  case "$key" in
+  '[A') # Up arrow
+    ((selected--))
+    if [ $selected -lt 0 ]; then
+      selected=$((${#options[@]} - 1))
+    fi
+    ;;
+  '[B') # Down arrow
+    ((selected++))
+    if [ $selected -ge ${#options[@]} ]; then
+      selected=0
+    fi
+    ;;
+  '') # Enter key
+    clear
+    echo "You selected: ${options[$selected]}"
+
+    # Handle the selection
+    case $selected in
+    0) echo "Installing package..." ;;
+    1) echo "Updating system..." ;;
+    2) echo "Viewing logs..." ;;
+    3) echo "Configuring settings..." ;;
+    4)
+      echo "Goodbye!"
+      exit 0
+      ;;
+    esac
+
+    echo ""
+    echo "Press any key to return to menu..."
+    read -n1
+    ;;
+  esac
+done
+```
+
+</bonus-content>