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Terminal Markdown Viewer

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When you edit multiple md files remotely, like in a larger mkdocs project, context switches between editing terminal(s) and viewing browser may have some efficiency impact. Also sometimes there is just no browser, like via security gateways offering just a fixed set of applications on the hop in machine. Further, reading efficiency and convenience is often significantly improved by using colors. And lastly, using such a thing for cli applications might improve user output, e.g. for help texts.

This is where mdv, a Python based Markdown viewer for the terminal might be a good option.

<!-- toc --> <!-- tocstop -->

If markdown is often "simple" enough to be somewhat readable on 256 color terminals (except images that is).

<img src="./samples/1.png" width=500>

from

### Source
# Header 1
## Header 2
### Header 3
#### Header 4
##### Header 5
###### Header 6
```python
""" Test """
# Make Py2 >>> Py3:
import os, sys; reload(sys); sys.setdefaultencoding('utf-8')
# no? see http://stackoverflow.com/a/29832646/4583360 ...

# code analysis for hilite:
try:
    from pygments import lex, token
    from pygments.lexers import get_lexer_by_name, guess_lexer
```

| Tables | Fmt |
| -- | -- |
| !!! hint: wrapped | 0.1 **strong** |

!!! note: title
    this is a Note

You can also use mdv as a source code viewer, best when you have docstrings with markdown in your code:

from

~/terminal_markdown_viewer $ cat setup.py
#!/usr/bin/env python2.7
# coding: utf-8

"""_
# Mdv installation

## Usage

    [sudo] ./setup.py install

----
"""

from setuptools import setup, find_packages

import mdv

setup(
    name='mdv',
    version=mdv.__version__,

(the '_' after the docstring telling mdv that markdown follows)

mdv is a proof of concept hack: While for simple structures it does its job quite well, for complex markdown you want to use other tools. Especially for inlined html it simply fails.

Features

Alternatives

The ones I know of (and which made me write mdv ;-) ):

  1. There are quite a few from the js community (e.g. msee, ansidown, ansimd and also nd which is great) but they require nodejs & npm, which I don't have on my servers. Also I personally wanted table handling and admonition support throughout and prob. too old to hack other peoples' js (struggling enough with my own). But have a look at them, they do some things better than mdv in this early version (I try to learn from them). Also this would be worth a look ;-)
  2. pandoc -> html -> elinks, lynx or pandoc -> groff -> man. (Heavy and hard to use from within other programs. Styling suboptimal)
  3. vimcat (Also heavy and hard to use inline in other programs)

Summary: For production ready robust markdown viewing (e.g. for your customers) I recommend nd still, due to the early state of mdv. For playing around, especially with theming or when with Python, this one might be a valid alternative to look at.

Installation

pip install mdv

If you get no attribute HTML_PLACEHOLDER: update your markdown package.

Here is a macport (thanks Aljaž).

mdv is also available in the FreeBSD package repositories via pkg install py36-mdv (the Python version might change in the future).

Manual Install: Requirements

Further a 256 color terminal (for now best with dark background) and font support for a few special separator characters (which you could change via config).

For light terms you'd just need to revert the 5 colors from the themes, since they are sorted by luminocity.

I did not test anything on windows.

Usage

CLI


# Usage:

    mdv [OPTIONS] MDFILE

# Options:

    MDFILE    : Path to markdown file
    -A        : Strip all ansi (no colors then)
    -C MODE   : Sourcecode highlighting mode
    -H        : Print html version
    -L        : Backwards compatible shortcut for '-u i'
    -M DIR    : Monitor directory for markdown file changes
    -T C_THEME: Theme for code highlight. If not set: Using THEME.
    -X Lexer  : Default lexer name (default: python). Set -x to use it always.
    -b TABL   : Set tab_length to sth. different than 4 [default: 4]
    -c COLS   : Fix columns to this (default: your terminal width)
    -f FROM   : Display FROM given substring of the file.
    -h        : Show help
    -i        : Show theme infos with output
    -l        : Light background (not yet supported)
    -m        : Monitor file for changes and redisplay FROM given substring
    -n NRS    : Header numbering (default: off. Say e.g. -3 or 1- or 1-5
    -t THEME  : Key within the color ansi_table.json. 'random' accepted.
    -u STYL   : Link Style (it=inline table=default, h=hide, i=inline)
    -x        : Do not try guess code lexer (guessing is a bit slow)


# Notes:

We use stty tool to derive terminal size. If you pipe into mdv we use 80 cols.

## To use mdv.py as lib:

Call the main function with markdown string at hand to get a
formatted one back. Sorry then for no Py3 support, accepting PRs if they don't screw Py2.

## FROM:

FROM may contain max lines to display, seperated by colon.
Example:

    -f 'Some Head:10' -> displays 10 lines after 'Some Head'

If the substring is not found we set it to the *first* character of the file -
resulting in output from the top (if your terminal height can be derived correctly through the stty cmd).

## Code Highlighting

Set -C <all|code|doc|mod> for source code highlighting of source code files.
Mark inline markdown with a '_' following the docstring beginnings.

- all: Show markdown docstrings AND code (default if you say, e.g. `-C.`)
- code: Only Code
- doc: Only docstrings with markdown
- mod: Only the module level docstring


## File Monitor:

If FROM is not found we display the whole file.

## Directory Monitor:

We check only text file changes, monitoring their size.

By default .md, .mdown, .markdown files are checked but you can change like `-M 'mydir:py,c,md,'` where the last empty substrings makes mdv also monitor any file w/o extension (like 'README').

### Running actions on changes:

If you append to `-M` a `'::<cmd>'` we run the command on any change detected (sync, in foreground).

The command can contain placeholders:

    _fp_     # Will be replaced with filepath
    _raw_    # Will be replaced with the base64 encoded raw content
               of the file
    _pretty_ # Will be replaced with the base64 encoded prettyfied output

Like: mdv -M './mydocs:py,md::open "_fp_"'  which calls the open
command with argument the path to the changed file.

## Docker

Should work w/o problems. See e.g. [here](https://github.com/axiros/terminal_markdown_viewer/issues/60) regarding how.


## Themes

### Theme Rollers


    mdv -T all [file]:  All available code styles on the given file.
    mdv -t all [file]:  All available md   styles on the given file.
                        If file is not given we use a short sample file.

So to see all code hilite variations with a given theme:

Say C_THEME = all and fix THEME

Setting both to all will probably spin your beach ball...

### Environ Vars

`$MDV_THEME` and `$MDV_CODE_THEME` are understood, e.g. `export
MDV_THEME=729.8953` in your .bashrc will give you a consistent color scheme.

Regarding the strange theme ids: Those numbers are the calculated total luminocity of the 5 theme colors.

Inline

mdv is designed to be used well from other (Py2) programs when they have md at hand which should be displayed to the user:

import mdv

# config like this:
mdv.term_columns = 60

# calling like this (all CLI options supported, check def main
formatted = mdv.main(my_raw_markdown, c_theme=...)

Note that I set the defaultencoding to utf-8 in __main__. I have this as my default python2 setup and did not test inline usage w/o. Check this for risks.

Sample Inline Use Case: click module docu

Armin Ronacher's click is a great framework for writing larger CLI apps - but its help texts are a bit boring, intended to be customized.

Here is how:

Write a normal click module with a function but w/o a doc string as shown:

@pass_context                                                                   
def cli(ctx, action, name, host, port, user, msg):           
	""" docu from module __doc__ """

On module level you provide markdown for it, like:

~/axc/plugins/zodb_sub $ cat zodb.py | head
"""
# Fetch and push ZODB trees

## ACTION: < info | pull | push | merge | dump | serve>

- info:  Requests server availability information
(...)

which you set at click module import time:

mod.cli.help = mod.__doc__

Lastly do this in your app module:

from click.formatting import HelpFormatter
def write_text(self, text):
    """ since for markdown pretty out on cli I found no good tool
	so I built my own """
    # poor man's md detection:
    if not text.strip().startswith('#'):
        return orig_write_text(self, text)
    from axc.markdown.mdv import main as mdv
    self.buffer.append(mdv(md=text, theme=os.environ['AXC_THEME']))

HelpFormatter.orig_write_text = HelpFormatter.write_text
HelpFormatter.write_text = write_text

The output has then colors:

and at smaller terms rewraps nicely:

Further, having markdown in the module __doc__ makes it simple to add into a global project docu framework, like mkdocs.

Customization

You can supply all CLI args in $HOME/.mdv, in yaml format.

More flex you have via $HOME/.mdv.py, which is execed if present, when running main.

Alternatively, in mdv.py you can change some config straight forward.

# ---------------------------------------------------------------------- Config
txt_block_cut, code_pref, list_pref, br_ends = '✂', '| ', '- ', '◈'
# ansi cols (default):
# R: Red (warnings), L: low visi, BG: background, BGL: background light, C=code
# H1 - H5 = the theme, the numbers are the ansi color codes:
H1,  H2,  H3,  H4,  H5, R,   L,  BG, BGL, T,   TL, C   = \
231, 153, 117, 109, 65, 124, 59, 16, 188, 188, 59, 102
# Code (C is fallback if we have no lexer). Default: Same theme:
CH1, CH2, CH3, CH4, CH5 = H1, H2, H3, H4, H5

code_hl = { "Keyword" : 'CH3', "Name" : 'CH1',
            "Comment" : 'L',  "String": 'CH4',
            "Error"   : 'R',  "Number": 'CH4',
            "Operator": 'CH5',
            "Generic" : 'CH2'
            }

admons = {'note'     : 'H3', 'warning': 'R',
          'attention': 'H1', 'hint'   : 'H4',
          'summary'  : 'H1', 'hint'   : 'H4',
          'question' : 'H5', 'danger' : 'R',
          'caution'  : 'H2'
         }

def_lexer = 'python'
guess_lexer = True
# also global. but not in use, BG handling can get pretty involved...
background = BG

# normal text color:
color = T

show_links = None

# could be given, otherwise read from ansi_tables.json:
themes = {}


# sample for the theme roller feature:
md_sample = ''

# ------------------------------------------------------------------ End Config

Any importing module can overwrite those module global variables as well.

Should you need yet additional themes, add them to ansi_tables.json file by adding your ansi codes there.

Screenshots

Random results, using the theme roller feature:

second

Note the table block splitting when the table does not fit (last picture).

TODO

PerfTests

Rendering this readme 100 times:

black root@ip-10-34-2-19:~/terminal_markdown_viewer/mdv/misc# python perfest.py
0.03 paka
0.04 paka_breaks
0.04 paka_xml
1.47 mistletoe
8.70 markdown
5.22 commonmark

mistletoe downside: py2 only via a fork.

Credits

pygments (using their lexer)

tabulate

and, naturally, the python markdown project

Updates

July 2016:

Sort of an excuse for the long long time w/o an update: I did actually start working on a more solid version based on CommonMark but that went a bit out of scope, into a general html terminal viewer, which will probably never be finished :-/

So at least here an update containing the stuff you guys sent as PRs, thanks all!!

Also:

Nov 2016:

Sept 2018:

Sept 2023: