Read Markdown as man pages with lowdown and mandoc

My use case, broadly speaking, is similar to that of many others that maintain a blog. I write my blog in Markdown and often want to check the output to make sure that it’s sane before applying changes.

Formerly, my way of addressing this was to run httpd(8) on localhost and use a shell script I wrote called webtest to render the output. Then, I would preview the changes in my web browser by visiting http://localhost/.

I do still like this method for certain things, such as seeing how CSS is going to look in Firefox. It’s nice to have a completely local, browsable copy of my website.1 However, for quickly ascertaining whether the output for an article is good or not, or to look over one or two articles, this is totally overkill!

This is where lowdown comes in. lowdown has a number of different output modes that can be specified with lowdown -T [mode]. lowdown -T html is typical for blogs.

One day, I got curious and read the man page to look for other output modes and noticed lowdown -T man. Suddenly, it hit me that I could use mandoc(1) to accept, format, and paginate that output like so:

$ lowdown -T man [Markdown file] | mandoc -a

So, it turns out I can RTFM even when proofreading my website. I use this trick enough that I wrote a small shell function named manmd() to save a few keystrokes.

Output can be piped to something other than mandoc if preferred–I use mandoc because it’s included with OpenBSD.

Other options for reading Markdown

It’s worth perusing the respective man pages for interesting options. Looking at mandoc, it’s possible to render lowdown -T man output as a PDF and pipe that into a PDF reader (I like zathura):

$ lowdown -T man [Markdown file] | mandoc -T pdf | zathura -

There is also lowdown -T term, described as “ANSI-escaped UTF-8 output suitable for reading on the terminal.” Here, I paginate the output with less(1), with -R to correctly interpret ANSI color escape sequences.

$ lowdown -T term [Markdown file] | less -R

To disable ANSI color escape sequences (I find the added color doesn’t enhance readability; if anything, it’s very distracting), use --term-no-colour:

$ lowdown -T term --term-no-colour [Markdown file] | less

I also wrote a small shell function for the no color variant of lowdown -T term, readmd(), just in case I feel like comparing or switching things up. The output is fairly similar, but there are a couple of small readability differences that keep me using lowdown -T man over lowdown -T term.

  1. I realize one could get more or less the same effect without running a web server on localhost (by pointing Firefox at the HTML files directly), but I like this method better. The application of unveil(2) to the Firefox package in OpenBSD means that Firefox has limited permissions as to what it can read, write, execute, and create, and I don’t want my website cluttering my ~/Downloads folder.