Scripts to embed LaTeX in Markdown documents

README.md

Hi! This is a pair of scripts to easily embed LaTeX figures in Markdown documents.

Before using them, please

1. modify TEX_DIR to be the folder where you want to keep the LaTeX stuff (./attachments/diagrams will be fine if you're using Obsidian);
2. modify PREAMBLE and POSTAMBLE the LaTeX code to sandwitch the code of your figures before compilation;
3. carefully read the scripts, as you're running Bash given to you by a stranger.

Then, you can use them like this:

# Extract figures from all your source files and update them
for file in **/*.md; do
  # This is overwriting the old files!
  cat file | ./diag-pluck.sh > diag-temp.md
  mv diag-temp.md file
done

# Check into your TEX_DIR
cd "./attachments/diagrams"

# Compile everything
latexmk

From time to time, you'll want to unclog your TEX_DIR by running something like

./diag-flush.sh **/*.md

Enjoy!

diag-flush.sh

#!/usr/bin/env bash

# USAGE:
#   ./diag-flush.sh **/*.md
# DESCRIPTION:
#   This utility gets a list of Markdown files,
#   gets the filenames of images with multiline alt text
#   which are in TEX_DIR, and deletes all files with
#   names that have no match in TEX_DIR.

TEX_DIR="./attachments/diagrams"

# NOTE: we're not regexp-escaping the leading dot in TEX_DIR,
# so there are some icky edge cases
readarray -d '' -t HASHES_TO_KEEP < <(grep --null -ohP "(?<=\]\(${TEX_DIR})[a-z0-9]{32}(?=.png\))" "$@")

echo $HASHES_TO_KEEP

shopt -s nullglob
for filename in "$TEX_DIR"/*; do
  echo $filename
	hash=${filename##*/}
	hash=${hash%%.*}
	if [[ ! ${HASHES_TO_KEEP[*]} =~ $hash ]]
	then
		echo Deleting $filename
		rm $filename
	fi
done

diag-pluck.sh

#!/usr/bin/env bash

# USAGE:
#   cat input.md | ./diag-pluck.sh > output.md
# DESCRIPTION:
#   This utility reads a Markdown file from stdin
#   and outputs a Markdown file to stdout.
#   All images with multiline alt text are detected, e.g.
#
#     ![
#     % Write any LaTeX code here.
#     %
#     % Leave no blank lines! Use a single if you need to.
#     ](./some/path/to/file.png)
#
#   and their alt text is enveloped in a template, hashed
#   and saved to a file in TEX_DIR.
#   The image tag url in the output is modified and points
#   to the homonimous image file in TEX_DIR.

TEX_DIR="./attachments/diagrams"
PREAMBLE="\documentclass{standalone}
\begin{document}
"
POSTAMBLE="\end{document}
"

reading=0
code=()

while IFS= read -r line; do
  if [[ "$line" =~ ^!\[$ ]]; then
    reading=1
    code=()
    echo "$line"
  elif [[ "$line" =~ ^\]\(.*\)$ ]]; then
    reading=0
    code="${PREAMBLE}${code}${POSTAMBLE}"
    md5=$(echo "$code" | md5sum | cut -d ' ' -f 1)
    echo -n "$code" > "${TEX_DIR}/${md5}.tex"
    echo "](${TEX_DIR}/${md5}.png)"
  elif [ "$reading" = 1 ]; then
    code+="${line}
" # this newline is not a typo!
    echo "$line"
  else
    echo "$line"
  fi

done