mdless

mdless is a utility that provides a formatted and highlighted view of Markdown files in Terminal.

I often use iTerm2 in visor mode, so qlmanage -p is annoying. I still wanted a way to view Markdown files quickly and without cruft.

Features

• Built in pager functionality with pipe capability, less replacement for Markdown files
• Format tables
• Colorize Markdown syntax for most elements
• Normalize spacing and link formatting
• Display footnotes after each paragraph
• Inline image display (local, optionally remote) if using iTerm2 2.9+
• Syntax highlighting when Pygments is installed
  • Only fenced code with a language defined (e.g. python) will be highlighted
  • Languages can also be determined by hashbang in the code block
• List headlines in document
  • Display single section of the document based on headlines
• Customizable colors
• Add iTerm marks for h1-3 navigation when pager is disabled

Installation

gem install mdless

Dependencies

Some OSs are missing tput, which is necessary for mdless.

apt update
apt install ruby ncurses-utils
gem install mdless

Usage

mdless [options] path or cat [path] | mdless

The pager used is determined by system configuration in this order of preference:

• $GIT_PAGER
• $PAGER
• git config --get-all core.pager
• bat
• less
• more
• cat
• pager

Options

-c, --[no-]color                 Colorize output (default on)
-d, --debug LEVEL                Level of debug messages to output
-h, --help                       Display this screen
-i, --images=TYPE                Include [local|remote (both)] images in output (requires imgcat and iTerm2, default NONE)
-I, --all-images                 Include local and remote images in output (requires imgcat and iTerm2)
    --links=FORMAT               Link style ([inline, reference], default inline) [NOT CURRENTLY IMPLEMENTED]
-l, --list                       List headers in document and exit
-p, --[no-]pager                 Formatted output to pager (default on)
-P                               Disable pager (same as --no-pager)
-s, --section=NUMBER             Output only a headline-based section of the input (numeric from --list)
-t, --theme=THEME_NAME           Specify an alternate color theme to load
-v, --version                    Display version number
-w, --width=COLUMNS              Column width to format for (default terminal width)

Customization

On first run a default theme file will be placed in ~/.config/mdless/mdless.theme. You can edit this file to modify the colors mdless uses when highlighting your files. You can copy this file and create multiple theme options which can be specified with the -t NAME option. For example, create ~/.config/mdless/brett.theme and then call mdless -t brett filename.md.

Colors are limited to basic ANSI codes, with support for bold, underline, italics (if available for the terminal/font), dark and bright, and foreground and background colors.

Customizeable settings are stored in YAML format. A chunk of the settings file looks like this:

h1:
  color: b intense_black on_white
  pad: d black on_white
  pad_char: "="

Font and color settings are set using a string of color names and modifiers. A typical string looks like b red on_white, which would give you a bold red font on a white background. In the YAML settings file there's no need for quotes, just put the string following the colon for the setting.

Some extra (non-color) settings are available for certain keys, e.g. pad_char to define the right padding character used on level 1 and 2 headlines. Note that you can change the Pygments theme used for syntax highlighting with the code_block.pygments_theme setting. For a list of available styles (assuming you have Pygments installed), use pygmentize -L styles.

Note: the ANSI escape codes are reset every time the color changes, so, for example, if you have a key that defines underlines for the url in a link, the underline will automatically be removed when it gets to a bracket. This also means that if you define a background color, you'll need to define it again on all the keys that it should affect.

Base colors:

• black
• red
• green
• yellow
• blue
• magenta
• cyan
• white

Emphasis:

• b (bold)
• d (dark)
• i (italic)
• u (underline)
• r (reverse, negative)

To modify the emphasis, use 'b' (bold), 'i' (italic), 'u' (underline), e.g. u yellow for underlined yellow. These can be combined, e.g. b u red.

Use 'r' to reverse foreground and background colors. r white on_black would display as black on_white. 'r' alone will reverse the current color set for a line.

To set a background color, use on_[color] with one of the 8 colors. This can be used with foreground colors in the same setting, e.g. white on_black.

Use 'd' (dark) to indicate the darker version of a foreground color. On macOS (and possibly other systems) you can use the brighter version of a color by prefixing with "intense", e.g. intense_red or on_intense_black.