[![Actions Status](https://github.com/tecolicom/App-mdee/actions/workflows/test.yml/badge.svg?branch=main)](https://github.com/tecolicom/App-mdee/actions?workflow=test) [![MetaCPAN Release](https://badge.fury.io/pl/App-mdee.svg)](https://metacpan.org/release/App-mdee) # NAME mdee - Markdown, Easy on the Eyes

# SYNOPSIS mdee [ options ] file ... -h --help show help --version show version -d --debug debug level (repeatable) -n --dryrun dry-run mode -s --style=# output style (nup/pager/cat/filter/raw) -f --filter shortcut for --style=filter -p --plain shortcut for --style=pager --[no-]fold line folding (default: on) --[no-]table table formatting (default: on) --[no-]nup nup paged output (default: on) -w --width=# fold width (default: 80) -t --theme=# color theme -m --mode=# light or dark (default: light) -B --base-color=# override theme's base color (e.g., Ivory, #780043, (120,0,67)) --list-themes list built-in themes --show=# set field visibility (e.g., italic=1) -C --pane=# number of columns -R --row=# number of rows -G --grid=# grid layout (e.g., 2x3) -P --page=# page height in lines -S --pane-width=# pane width (default: 85) --bs --border-style=# border style --[no-]pager[=#] pager command # VERSION Version 0.06 # DESCRIPTION **mdee** is a multi-column Markdown viewer with syntax highlighting, combining [greple(1)](http://man.he.net/man1/greple) for colorization and [nup(1)](http://man.he.net/man1/nup) for paged output. Supported elements: headers (h1-h6), bold, italic, strikethrough, inline code, code blocks, HTML comments, tables, and list items. This tool is designed for viewing Markdown not constrained by display formatting, such as output from LLMs (Large Language Models). It applies syntax highlighting with line folding and table alignment, but does not reflow paragraphs with hard line breaks. For full Markdown rendering, many other viewers are available. Combine them with [nup(1)](http://man.he.net/man1/nup) for similar paged output (e.g., `nup glow README.md`). # OPTIONS ## General Options - **-h**, **--help** Show help message. - **--version** Show version. - **-d**, **--debug** Set debug level. Can be repeated for increasing verbosity. - `-d` Show color values and pipeline stage names. - `-dd` Above, plus full command lines for each pipeline stage. - **-n**, **--dryrun** Dry-run mode. Show the pipeline without executing. With `-dd`, shows expanded command lines for each stage instead of function names. ## Processing Options - **-s** _STYLE_, **--style**=_STYLE_ Set the output style. Default is `nup`. Available styles: - `nup` - Full pipeline: fold + table + nup paged output (default) - `pager` - Fold + table, output to pager (`$PAGER` or `less`) - `cat` - Fold + table, output to stdout - `filter` - Table only (no fold, no nup), suitable for piping - `raw` - Highlight only (no fold, no table, no nup) The style sets the initial state of `--fold`, `--table`, and `--nup` options. Subsequent options can override individual settings: mdee -s filter --fold file.md # filter + fold mdee -p --no-fold file.md # pager without fold - **-f**, **--filter** Shortcut for `--style=filter`. Reads from stdin (or files) and outputs highlighted Markdown to stdout. Disables line folding and nup paged output, but keeps table formatting enabled. Useful for piping Markdown content through mdee for syntax highlighting. - **-p**, **--plain** Shortcut for `--style=pager`. Enables fold and table formatting, outputs through a pager (`$PAGER` or `less`) instead of nup. - **--\[no-\]fold** Enable or disable line folding for list items. When enabled, long lines in list items are wrapped with proper indentation using [ansifold(1)](http://man.he.net/man1/ansifold). Default is enabled. - **--\[no-\]table** Enable or disable table formatting. When enabled, Markdown tables are formatted using [ansicolumn(1)](http://man.he.net/man1/ansicolumn) for aligned column display. Default is enabled. - **--\[no-\]nup** Enable or disable [nup(1)](http://man.he.net/man1/nup) for multi-column paged output. When disabled, output goes directly to stdout without formatting. Default is enabled. - **-w** _N_, **--width**=_N_ Set the fold width for text wrapping. Default is 80. Only effective when `--fold` is enabled. ## Theme Options **mdee** supports color themes for customizing syntax highlighting. Themes define colors for various Markdown elements (headers, code blocks, bold text, etc.). - **-t** _NAME_, **--theme**=_NAME_ Select a color theme. Default is `default`. - **-m** _MODE_, **--mode**=_MODE_ Select light or dark mode. Default is `light`. If the terminal supports background color detection (via [Getopt::EX::termcolor](https://metacpan.org/pod/Getopt%3A%3AEX%3A%3Atermcolor)), the mode is automatically selected based on terminal luminance. Each theme has light and dark variants optimized for different terminal backgrounds. The built-in `default` theme uses RoyalBlue as the base color with automatic luminance adjustment: - `light` - RoyalBlue with luminance 25 (dark text for light backgrounds) - `dark` - RoyalBlue with luminance 80 (bright text for dark backgrounds) User configuration is loaded from: ${XDG_CONFIG_HOME:-~/.config}/mdee/config.sh This is a shell script that can set defaults and override colors: # ~/.config/mdee/config.sh default_mode='dark' # set default mode colors[base]='' # override base color colors[h1]='L25DE/${base}' # header with base background Color specifications use [Term::ANSIColor::Concise](https://metacpan.org/pod/Term%3A%3AANSIColor%3A%3AConcise) format. The `FG/BG` notation specifies foreground and background colors (e.g., `L25DE/${base}` means gray foreground on base-colored background). The `${base}` string is expanded to the base color value after loading. - **-B** _COLOR_, **--base-color**=_COLOR_ Override the theme's base color. The base color determines the overall color scheme because all heading colors (h1, h2, h3, etc.) are derived from it by adjusting luminance. For example, h2 might be `${base}+y20` (base color with luminance increased by 20). **Simple color name** - luminance is adjusted automatically: When you specify just a color name (without `<>` brackets or other syntax), the default luminance adjustment is applied based on the current mode: -B RoyalBlue # becomes =y25 in light mode # becomes =y80 in dark mode This makes it easy to try different colors without worrying about luminance values. The default adjustments (`=y25` for light, `=y80` for dark) are designed to provide good contrast against typical terminal backgrounds. **Full color specification** - used exactly as specified: If you include `<>` brackets, luminance modifiers, or use RGB notation, the value is used as-is without any automatic adjustment: -B '' # original color, no adjustment -B '=y50' # explicit luminance 50 -B '#780043' # burgundy in hex -B '(120,0,67)' # same color in RGB decimal **Customizing the default adjustment**: The automatic luminance adjustment values can be customized with the `--adjust` option: --adjust 'light==y30' # use =y30 instead of =y25 for light mode --adjust 'dark==y70' # use =y70 instead of =y80 for dark mode **Note**: Basic ANSI color codes (`R`, `G`, `B`, etc.) cannot be used because heading variations require luminance adjustment, which only works with full color specifications (X11 names, RGB hex, or RGB decimal). - **--list-themes** List built-in themes with color samples and exit. ## Highlight Options - **--show**=_FIELD_\[=_VALUE_\],... Control field visibility for highlighting. Empty value or `0` disables the field; any other value (including `1`) enables it. --show italic # enable italic --show bold=0 # disable bold --show all # enable all fields --show all= --show bold # disable all, then enable only bold Multiple fields can be specified with commas or by repeating the option. The special field `all` affects all fields and is processed first. Available fields: `comment`, `bold`, `italic`, `strike`, `h1`, `h2`, `h3`, `h4`, `h5`, `h6`, `inline_code`, `code_block`. All fields are enabled by default. ## Layout Options (passed to nup) - **-C** _N_, **--pane**=_N_ Set the number of columns (panes). - **-R** _N_, **--row**=_N_ Set the number of rows. - **-G** _CxR_, **--grid**=_CxR_ Set grid layout. For example, `-G2x3` creates 2 columns and 3 rows. - **-P** _N_, **--page**=_N_ Set the page height in lines. - **-S** _N_, **--pane-width**=_N_ Set the pane width in characters. Default is 85. - **--bs**=_STYLE_, **--border-style**=_STYLE_ Set the border style. ## Pager Options - **--\[no-\]pager**\[=_COMMAND_\] Set the pager command. Use `--pager=less` to specify a pager, or `--no-pager` to disable paging. # EXAMPLES mdee README.md # view markdown file mdee -C2 document.md # 2-column view mdee -G2x2 manual.md # 2x2 grid (4-up) mdee -w60 narrow.md # narrower text width mdee --no-pager file.md # without pager mdee --no-nup file.md # output to stdout without nup mdee --no-fold file.md # disable line folding mdee --no-table file.md # disable table formatting # Output styles mdee -s pager file.md # fold + table, output to pager mdee -s cat file.md # fold + table, output to stdout mdee -s filter file.md # table only, no fold/nup mdee -s raw file.md # highlight only # Style shortcuts mdee -p file.md # same as --style=pager cat file.md | mdee -f # highlight stdin (filter mode) mdee -f file.md # highlight only (no paging) # Override individual settings mdee -f --fold file.md # filter + fold mdee -p --no-fold file.md # pager without fold # Theme examples mdee --mode=dark file.md # use dark mode mdee --mode=light file.md # use light mode mdee -B Ivory file.md # override base color mdee --mode=dark -B '#780043' file.md # dark mode with burgundy mdee --list-themes # list available themes # INSTALLATION ## Homebrew (macOS) brew tap tecolicom/tap brew install app-mdee ## CPAN cpanm -n App::mdee # DEPENDENCIES This command requires the following: - [App::Greple](https://metacpan.org/pod/App%3A%3AGreple) - pattern matching and highlighting - [App::Greple::tee](https://metacpan.org/pod/App%3A%3AGreple%3A%3Atee) - filter integration - [App::ansifold](https://metacpan.org/pod/App%3A%3Aansifold) - ANSI-aware text folding - [App::ansicolumn](https://metacpan.org/pod/App%3A%3Aansicolumn) - ANSI-aware column formatting - [App::nup](https://metacpan.org/pod/App%3A%3Anup) - N-up multi-column paged output - [App::ansiecho](https://metacpan.org/pod/App%3A%3Aansiecho) - ANSI color output - [Getopt::Long::Bash](https://metacpan.org/pod/Getopt%3A%3ALong%3A%3ABash) - bash option parsing - [Getopt::EX::termcolor](https://metacpan.org/pod/Getopt%3A%3AEX%3A%3Atermcolor) - terminal background detection # IMPLEMENTATION **mdee** is implemented as a Bash script that orchestrates multiple specialized tools into a unified pipeline. The architecture follows Unix philosophy: each tool does one thing well, and they communicate through standard streams. The overall data flow is: Input File | v [greple] --- Syntax Highlighting | v [ansifold] --- Text Folding (optional) | v [ansicolumn] --- Table Formatting (optional) | v [nup] --- Paged Output (nup style) | or [pager] --- Pager Output (pager style) | v Terminal/Pager ## Pipeline Architecture **mdee** dynamically constructs a pipeline based on enabled options. Each stage is defined as a Bash function (e.g., `run_greple`, `run_fold`). The `--dryrun` option displays the function-based pipeline without execution. ### Processing Stages The pipeline consists of four configurable stages. Each stage can be enabled or disabled independently using `--[no-]fold`, `--[no-]table`, and `--[no-]nup` options. #### Syntax Highlighting The first stage uses [greple(1)](http://man.he.net/man1/greple) with the `-G` (grep mode) and `--ci=G` (capture index) options to apply different colors to each captured group in regular expressions. Supported Markdown elements: - Headers (`# h1` through `###### h6`) - Bold text (`**bold**` or `__bold__`) - Italic text (`*italic*` or `_italic_`) - Inline code (`` `code` ``) - Code blocks (fenced with ```` ``` ```` or `~~~`) - HTML comments (``) Code block detection follows the CommonMark specification: - Opening fence: 0-3 spaces indentation, then 3+ backticks or tildes - Closing fence: 0-3 spaces indentation, same character, same or more count - Backticks and tildes cannot be mixed (```` ``` ```` must close with ```` ``` ````) **Color Specifications** Colors are specified using [Term::ANSIColor::Concise](https://metacpan.org/pod/Term%3A%3AANSIColor%3A%3AConcise) format. The `--cm` option maps colors to captured groups. For example, `L00DE/${base}` specifies gray foreground on base-colored background. The color specification supports modifiers: - `+y10` / `-y10`: Adjust luminance by percentage - `=y50`: Set absolute luminance - `D`: Bold, `U`: Underline, `E`: Erase line Example greple invocation: greple -G --ci=G --all --need=0 \ --cm 'L00DE/${base}' -E '^#\h+.*' \ --cm '${base}D' -E '\*\*.*?\*\*' \ file.md #### Text Folding The second stage wraps long lines in list items using [ansifold(1)](http://man.he.net/man1/ansifold) via [Greple::tee](https://metacpan.org/pod/Greple%3A%3Atee). It preserves ANSI escape sequences and maintains proper indentation for nested lists. The folding width is controlled by `--width` option (default: 80). #### Table Formatting The third stage formats Markdown tables using [ansicolumn(1)](http://man.he.net/man1/ansicolumn). Tables are detected by the pattern `^(\|.+\|\n){3,}` and formatted with aligned columns while preserving ANSI colors. ### Output Stage The final stage uses [nup(1)](http://man.he.net/man1/nup) to provide multi-column paged output. Layout options (`--pane`, `--row`, `--grid`, `--page`) are passed directly to nup. ## Theme System **mdee** implements a theme system with light and dark mode variants. ### Theme Structure Each theme is defined as a Bash associative array with color definitions for each Markdown element. The `${base}` placeholder references the base color (set via `--base-color` option): declare -A theme_default_dark=( [h1]='L00DE/${base}' [h2]='L00DE/${base}-y15' [h3]='L00DN/${base}-y25' ... ) #### Base Color Expansion The `${base}` placeholder is expanded to the effective base color after theme loading. The base color is determined by the `--base-color` option (default: RoyalBlue) with automatic luminance adjustment based on mode (`=y25` for light, `=y80` for dark). #### Terminal Mode Detection **mdee** uses [Getopt::EX::termcolor](https://metacpan.org/pod/Getopt%3A%3AEX%3A%3Atermcolor) to detect terminal background luminance. If luminance is below 50%, dark mode is automatically selected. # LIMITATIONS ## HTML Comments Only HTML comments starting at the beginning of a line are highlighted. Inline comments are not matched to avoid conflicts with inline code containing comment-like text (e.g., `` `` ``). ## Emphasis Emphasis patterns (bold and italic) do not span multiple lines. Multi-line emphasis text is not supported. ## Links Link patterns do not span multiple lines. The link text and URL must be on the same line. Reference-style links (`[text][ref]` with `[ref]: url` elsewhere) are not supported. ## OSC 8 Hyperlinks Links are converted to OSC 8 terminal hyperlinks for clickable URLs: - `[text](url)` - `[text]` links to url - `![alt](url)` - `![alt]` links to url (image) - `[![alt](img)](url)` - `!` links to img, `[alt]` links to url This requires terminal support. Compatible terminals include iTerm2, Kitty, WezTerm, Ghostty, and recent versions of GNOME Terminal. Apple's default Terminal.app does not support OSC 8. When using `less` as pager, version 566 or later is required with `-R` option. For OSC 8 specification, see: [https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5fedd](https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5fedd) # SEE ALSO [nup(1)](http://man.he.net/man1/nup), [greple(1)](http://man.he.net/man1/greple), [ansifold(1)](http://man.he.net/man1/ansifold), [ansicolumn(1)](http://man.he.net/man1/ansicolumn) # AUTHOR Kazumasa Utashiro # LICENSE Copyright 2026 Kazumasa Utashiro. This software is released under the MIT License. [https://opensource.org/licenses/MIT](https://opensource.org/licenses/MIT)