title: Comprehensive Markdown & GFM Syntax Reference
desc: A detailed guide to Markdown and GitHub Flavored Markdown (GFM) syntax, covering text formatting, lists, tables, code blocks, links, and footnotes.
date: 2026-05-27
tags: [markdown, gfm, syntax, reference, guide]
draft: true
^---

## 1. Text Formatting & Structure

*   **Bold:** **This text is bold** or __this is bold__.
*   **Italic:** *This text is italic* or _this is italic_.
*   **Strikethrough (GFM):** ~~This text is crossed out.~~
*   **Combined:** ***This text is bold and italic***.
*   **Inline Code:** Use single backticks for `console.log("Hello World")` inline.

### Hierarchy Example
> **Blockquotes:** Use blockquotes to highlight quotes, notes, or warnings.
> 
> "The best way to predict the future is to invent it."
> > Nested blockquotes are supported by adding an extra `>`.

---

## 2. Lists

### Unordered (Bulleted)
*   Item 1
    *   Nested Item 1.1
    *   Nested Item 1.2
*   Item 2

### Ordered (Numbered)
1.  First item
2.  Second item
    1.  Nested ordered item
    2.  Another nested item
3.  Third item

### Task Lists (GFM)
- [x] Write the Markdown test template
- [ ] Implement features in production
- [ ] Review documentation

---

## 3. Tables (GFM)

| Feature | Standard Markdown | GFM Extension | Status |
| :--- | :---: | :---: | ---: |
| Tables | ✗ | ✓ | Implemented |
| Task Lists | ✗ | ✓ | Implemented |
| Autolinks | ✗ | ✓ | Native |
| Strikethrough | ✗ | ✓ | Implemented |

---

## 4. Code Blocks with Syntax Highlighting

```bash
#!/usr/bin/env bash
set -euo pipefail

# Variables & string manipulation
NAME="world"
GREETING="Hello, ${NAME}!"
UPPER=${GREETING^^}
SLICE=${GREETING:0:5}
echo "$UPPER | $SLICE"

# Arrays
FRUITS=(apple banana cherry)
FRUITS+=(mango)
echo "${FRUITS[@]}"          # all elements
echo "${#FRUITS[@]}"         # length
echo "${FRUITS[@]:1:2}"      # slice

# Associative array
declare -A CONFIG=([host]="localhost" [port]="8080")
echo "${CONFIG[host]}:${CONFIG[port]}"

# Arithmetic
COUNT=0
(( COUNT += 5 ))
RESULT=$(( COUNT ** 2 ))
echo "$RESULT"

# Conditionals & test operators
FILE="/etc/hosts"
if [[ -f "$FILE" && -r "$FILE" ]]; then
  echo "readable"
elif [[ -e "$FILE" ]]; then
  echo "exists but not readable"
else
  echo "not found"
fi

# Case
case "$NAME" in
  world|earth) echo "planet" ;;
  *) echo "unknown" ;;
esac

# Loops
for fruit in "${FRUITS[@]}"; do
  echo "fruit: $fruit"
done

for (( i=0; i<3; i++ )); do
  echo "i=$i"
done

WHILE=3
while (( WHILE-- > 0 )); do
  echo "while: $WHILE"
done

# Functions with local vars & return codes
greet() {
  local name=${1:-"stranger"}
  local -r greeting="Hi, $name!"
  echo "$greeting"
  return 0
}
greet "$NAME"

# Command substitution & process substitution
DATE=$(date +%Y-%m-%d)
DIFF=<(echo "foo") 
echo "Today: $DATE"

# Here-doc
cat <<EOF
Multiline
  text block
EOF

# Pipelines, redirection & traps
trap 'echo "exiting"; exit 1' ERR
echo "hello" | tr '[:lower:]' '[:upper:]' > /dev/null 2>&1

# Parameter expansion: default, error, replace
echo "${UNSET:-default}"
echo "${GREETING/Hello/Hey}"
echo "${FILE##*/}"   # basename
echo "${FILE%/*}"    # dirname
```

---

## 5. Links and Autolinks

*   **Standard Link:** [Search Engine](https://www.google.com)
*   **Link with Tooltip:** [GitHub](https://github.com "Go to GitHub")
*   **Autolink (GFM):** https://nixos.org