Parse Frontmatter

1#!/bin/bash
2# Frontmatter Parser Utility
3# Extracts YAML frontmatter from .local.md files
4
5set -euo pipefail
6
7# Usage
8show_usage() {
9  echo "Usage: $0 <settings-file.md> [field-name]"
10  echo ""
11  echo "Examples:"
12  echo "  # Show all frontmatter"
13  echo "  $0 .claude/my-plugin.local.md"
14  echo ""
15  echo "  # Extract specific field"
16  echo "  $0 .claude/my-plugin.local.md enabled"
17  echo ""
18  echo "  # Extract and use in script"
19  echo "  ENABLED=\$($0 .claude/my-plugin.local.md enabled)"
20  exit 0
21}
22
23if [ $# -eq 0 ] || [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
24  show_usage
25fi
26
27FILE="$1"
28FIELD="${2:-}"
29
30# Validate file
31if [ ! -f "$FILE" ]; then
32  echo "Error: File not found: $FILE" >&2
33  exit 1
34fi
35
36# Extract frontmatter
37FRONTMATTER=$(sed -n '/^---$/,/^---$/{ /^---$/d; p; }' "$FILE")
38
39if [ -z "$FRONTMATTER" ]; then
40  echo "Error: No frontmatter found in $FILE" >&2
41  exit 1
42fi
43
44# If no field specified, output all frontmatter
45if [ -z "$FIELD" ]; then
46  echo "$FRONTMATTER"
47  exit 0
48fi
49
50# Extract specific field
51VALUE=$(echo "$FRONTMATTER" | grep "^${FIELD}:" | sed "s/${FIELD}: *//" | sed 's/^"\(.*\)"$/\1/' | sed "s/^'\\(.*\\)'$/\\1/")
52
53if [ -z "$VALUE" ]; then
54  echo "Error: Field '$FIELD' not found in frontmatter" >&2
55  exit 1
56fi
57
58echo "$VALUE"
59exit 0