# `$ mdsh` - a markdown shell pre-processor [![Build Status](https://github.com/zimbatm/mdsh/actions/workflows/ci.yaml/badge.svg)](https://github.com/zimbatm/mdsh/actions/workflows/ci.yaml?branch=master) [![crates.io](https://img.shields.io/crates/v/mdsh.svg)](https://crates.io/crates/mdsh) The mdsh project describes a Markdown language extension that can be used to automate some common tasks in README.md files. Quite often I find myself needing to embed a snippet of code or markdown from a different file. Or I want to show the output of a command. In both cases this can be done manually, but what all you had to do was run `mdsh` and have the file updated automatically? So the goal of this tool is first to extend the syntax of Markdown in a natural way. Something that you might type. And if the `mdsh` tool is run, the related blocks get updated in place. Most other tools would produce a new file but we really want a sort of idempotent operation here. In the end this gives a tool that is a bit akin to literate programming or jupyer notebooks but for shell commands. It adds a bit of verbosity to the file and in exchange it allows to automate the refresh of those outputs. ## Usage `$ mdsh --help` ``` mdsh 0.6.0 Markdown shell pre-processor. Never let your READMEs and tutorials get out of sync again. Exits non-zero if a sub-command failed. USAGE: mdsh [FLAGS] [OPTIONS] FLAGS: --clean Remove all generated blocks --frozen Fail if the output is different from the input. Useful for CI. Using `--frozen`, you can guarantee that developers update documentation when they make a change. Just add `mdsh --frozen` as a check to your continuous integration setup. -h, --help Prints help information -V, --version Prints version information OPTIONS: -i, --inputs ... Path to the markdown files. `-` for stdin [default: ./README.md] -o, --output Path to the output file, `-` for stdout [defaults to updating the input file in-place] --work_dir Directory to execute the scripts under [defaults to the input file’s directory] ``` ## Syntax Extensions ### Inline Shell Code Syntax regexp: ```regexp ^`[$>] ([^`]+)`\s*$ ``` Inline Shell Code are normal `inline code` that: * start at the beginning of a line * include either `$` or `>` at the beginning of their content * contain a shell command When those are enountered, the command is executed by `mdsh` and output as either a fenced code block (`$`) or markdown code (`>`). * `$` runs the command and outputs a code block * `>` runs the command and outputs markdown Examples: ~~~ `$ seq 4 | sort -r` ``` 4 3 2 1 ``` ~~~ ~~~ `> echo 'I *can* include markdown. Hehe.'` I *can* include markdown. Hehe. ~~~ ### Variables Syntax regexp: ```regexp ^`! ([\w_]+)=([^`]+)`\s*$ ``` Variables allow you to set new variables in the environment and reachable by the next blocks that are being executed. The value part is being evaluated by bash and can thus spawn sub-shells. Examples: `! user=bob` Now the $user environment variable is available: `$ echo hello $user` ``` hello bob ``` Now capitalize the user `! USER=$(echo $user | tr '[[:lower:]]' '[[:upper:]]')` `$ echo hello $USER` ``` hello BOB ``` ### Link Includes Syntax regexp: ```regexp ^\[[$>] ([^\]]+)]\([^\)]+\)\s*$ ``` Link Includes work similarily to code blocks but with the link syntax. * `$` loads the file and embeds it as a code block * `>` loads the file and embeds it as markdown Examples: ~~~ [$ code.rb](samples/code.rb) as ruby ```ruby require "pp" pp ({ foo: 3 }) ``` ~~~ ~~~ [> example.md](samples/example.md) *this is part of the example.md file* ~~~ ### ANSI escapes ANSI escape sequences are filtered from command outputs: `$ echo $'\e[33m'yellow` ``` yellow ``` ### Commented-out commands Sometimes it's useful not to render the command that is being shown. All the commands support being hidden inside of a HTML comment like so: ~~~ ``` example ``` ~~~ ### Fenced code type If you want GitHub to highlight the outputted code fences, it's possible to postfix the line with `as `. For example: ~~~ `$ echo '{ key: "value" }'` as json ```json { key: "value" } ``` ~~~ ## Installation The best way to install `mdsh` is with the rust tool cargo. ```bash cargo install mdsh ``` If you are lucky enough to be a nix user: ```bash nix-env -f https://github.com/NixOS/nixpkgs/archive/master.tar.gz -iA mdsh ``` ### Pre-commit hook This project can also be installed as a [pre-commit](https://pre-commit.com/) hook. Add to your project's `.pre-commit-config.yaml`: ```yaml - repo: https://github.com/zimbatm/mdsh.git rev: master hooks: - id: mdsh ``` Make sure to have rust available in your environment. Then run `pre-commit install-hooks` ## Known issues The tool currently lacks in precision as it doesn't parse the Markdown file, it just looks for the desired blocks by regexp. It means that in some cases it might misintepret some of the commands. Most existing Markdown parsers are used to generate HTML in the end and are thus not position-preserving. Eg: pulldown-cmark The block removal algorithm doesn't support output that contains triple backtick or ``. ## Related projects * is the closest to this project. It has some interesting Pandoc filters that capture code blocks into outputs. The transformation is not in-place like `mdsh`. * [Literate Programming](https://en.wikipedia.org/wiki/Literate_programming) is the practice of interspesing executable code into documents. There are many language-specific implementations out there. `mdsh` is a bit like a bash literate programming language. * [Jupyter Notebooks](https://jupyter.org/) is a whole other universe of documentation and code. It's great but stores the notebooks as JSON files. A special viewer program is required to render them to HTML or text. ## User Feedback ### Issues If you have any problems with or questions about this project, please contact use through a [GitHub issue](https://github.com/zimbatm/mdsh/issues). ### Contributing You are invited to contribute new features, fixes or updates, large or small; we are always thrilled to receive pull requests, and do our best to process them as fast as we can. ## License [> LICENSE](LICENSE) MIT License Copyright (c) 2019 zimbatm and contributors Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.