Ubuntu Manpage: lowdown-diff — view differences in markdown files

NAME

       lowdown-diff — view differences in markdown files

SYNOPSIS

       lowdown-diff  [input_options]  [output_options]  [-s]  [-M  metadata]  [-m  metadata] [-o file] [-T mode]
                    oldfile [newfile]

DESCRIPTION

Shows differences between lowdown(5) documents as formatted output. Results are written to standard
output.

The arguments are as follows:

-s Standalone mode. This emits a document envelope surrounding the output by drawing from document
metadata. See “Metadata” on providing information to the document envelope. This applies to
-Tgemini, -Thtml, -Tlatex, -Tms, -Tman, and -Tfodt.

-M metadata
Provide a single metadata key-value pair. This may be in the usual lowdown(5) colon-separated
metadata format or instead separated by an equal sign, depending upon which character comes
first. Exits with an error if given neither colon nor equal sign. May be invoked multiple times
for each pair. This overrides -m and what's parsed from the document.

-m metadata
Like -M, but is overridden by what's parsed the document, then -M.

-o file
Send output to file unless it's “-”, in which case fall back to the default of standard output.

-T mode
The output mode. This may be html for HTML5 output, latex for LaTeX, gemini for the Gemini
format, ms for roff output using the classic (i.e., no-extension) -ms package and needing table
support, term for ANSI-compatible UTF-8 terminal output, man for roff output using the classic
-man package, tree, to show the parse tree of the input document, and null to parse the document
but do no rendering. See “Output modes”.

oldfile, newfile
Markdown documents used for comparison. If newfile is not given or “-”, it is read from standard
input.

The following are options for input parsing. These affect the parse tree passed to all outputs.

--parse-hilite
Enable highlight span support. This are disabled by default because it may be erroneously
interpreted as section headers.

--parse-math
Recognise mathematics equations.

--parse-maxdepth=depth
The maximum depth of nested elements. This defaults to 128, which is probably more than enough
for any real-world document. If the maximum is hit, the system exits as if memory were
exhausted. Set to zero for no maximum.

--parse-no-autolink
Do not parse http, https, ftp, mailto, and relative links or link fragments.

--parse-no-cmark
Do not parse with CommonMark constraints. This also disables using the first ordered list value
instead of starting all lists at one.

--parse-no-codeindent
Do not parse indented content as code blocks.

--parse-no-deflists
Do not parse PHP extra definition lists.

--parse-no-fenced
Do not parse GFM fenced (language-specific) code blocks.

--parse-no-footnotes
Do not parse MMD footnotes.

--parse-no-img-ext
Deprecated. See --parse-no-ext-attrs.

--parse-no-intraemph
Do not parse emphasis within words and links.

--parse-no-metadata
Do not parse MMD metadata. For the first paragraph to count as metadata, the first line must
have a colon in it. This does not affect metadata given on -m or -M.

--parse-no-strike
Do not parse strikethroughs.

--parse-no-super
Do not parse super-scripts.

--parse-no-tables
Do not parse GFM tables.

--parse-no-tasklists
Do not parse GFM task lists.

There are many output options. The following are shared by all output modes:

--out-standalone
Alias for -s.

--out-no-smarty
Do not use the smart typography filter. By default, certain character sequences are translated
into output-specific glyphs.

What follows are per-output options. For HTML with -Thtml, these are as follows:

--html-hardwrap
Hard-wrap paragraph content by outputting line breaks where applicable.

--html-no-escapehtml
If --html-no-skiphtml has been specified, this causes embedded HTML not to be escaped, and is
instead output verbatim. This has no effect if --html-no-skiphtml has not been specified.

--html-no-head-ids
Do not output id attributes for headers.

--html-no-num-ent
Don't normalise HTML entities (when possible) as numeric ones and instead use the entities as
given on input.

--html-no-owasp
Don't follow the OWASP recommendations for escaping text, and do only the minimal escaping to
make sure that regular content isn't interpreted as HTML.

--html-no-skiphtml
Output embedded HTML. By default, embedded HTML is not output at all. See --html-no-escapehtml.

For both -Tman and -Tms, the following apply:

--nroff-no-groff
Don't use groff(1) style section headings, PDF hyperlinks and multi-page tables (these further
require -Tms mode and -mspdf passed to groff(1)), or Unicode sequence syntax. The output is
compatible with traditional troff(1). Applies to -Tman and -Tms.

--nroff-no-numbered
Don't output numbered headings. Only applies to -Tms.

--nroff-no-skiphtml
Output embedded HTML. This usually doesn't make sense because the HTML won't be interpreted by
the output reader. By default, HTML is omitted.

--nroff-nolinks
Don't show URLs for images and links (autolinks are still shown). (Link content is still shown.)
Overrides --nroff-shortlinks for images and links. Applies to -Tman or when -nroff-no-groff is
specified.

--nroff-shortlinks
Shorten URLs for images, links, and autolinks to only the domain name and final path. Applies to
-Tman or when -nroff-no-groff is specified.

The -Tterm output has the following:

--term-columns=columns
The number of columns in the screen. Useful for when running in a pipe. Defaults to what the
terminal reports or 72 if in a pipe.

--term-hmargin=margin
The number of left margin spaces. Truncated to the number of columns. Defaults to zero.

--term-no-ansi
Don't show ANSI styles at all. This implies --term-no-colour.

--term-no-colour
Don't show ANSI colours. This will still decorate text with underlines, bolds, and italics, but
not emit any colour codes.

--term-nolinks
Don't show URLs for images and links (autolinks are still shown). (Link content is still shown.)
Overrides --term-shortlinks for images and links.

--term-shortlinks
Shorten URLs for images, links, and autolinks to only the domain name and final path.

--term-vmargin=margin
The number of top and bottom margin newlines. Defaults to zero.

--term-width=width
Set the soft limit on the number of characters per line. This may be exceeded by literal text.
The default (or if zero) is the number of terminal columns or 80 at most.

The -Tgemini output has several flags that control the placement of links. By default, links (images,
autolinks, and links) are queued when specified in-line then emitted in a block sequence after the
nearest block element.

--gemini-link-end
Emit the queue of links at the end of the document instead of after the nearest block element.

--gemini-link-inline
Render all links within the flow of text. This will cause breakage when nested links, such as
images within links, links in blockquotes, etc. It should not be used unless in carefully
crafted documents.

--gemini-link-noref
Do not format link labels. Takes precedence over --gemini-link-roman.

--gemini-link-roman
When formatting link labels, use lower-case Roman numerals instead of the default lower-case
hexavigesimal (i.e., “a”, “b”, ..., “aa”, “ab”, ...).

--gemini-metadata
Print metadata as the canonicalised key followed by a colon then the value, each on one line
(newlines replaced by spaces). The metadata block is terminated by a double newline. If there
is no metadata, this does nothing.

The -Tlatex output has the following options:

--latex-no-numbered
Don't number sections (and subsections, etc.).

--latex-no-skiphtml
Output embedded HTML. This usually doesn't make sense because the HTML won't be interpreted by
the output reader. By default, HTML is omitted.
The -Tfodt output has the following options:

--odt-no-skiphtml
Output embedded HTML. This usually doesn't make sense because the HTML won't be interpreted by
the output reader. By default, HTML is omitted.

Metadata
If parsed from the document or as given by -m or -M, the following metadata keys are recognised by output
front-ends. The metadata keys are canonicalised in lowercase and without spaces.

Metadata values should not be encoded in their output format, e.g., “css: foo&amp;bar”. The renderer
will perform any necessary output encoding.

affiliation
Author affiliation (organisation or institution). Multiple affiliations may be separated by two
or more spaces (including newlines). Used in -Thtml, -Tlatex, and -Tms.

author Document author. Multiple authors may be separated by two or more spaces (including newlines).
Overridden by rcsauthor. Used in -Tfodt, -Thtml, -Tlatex, and -Tms.

baseheaderlevel
Added to each header level. Deprecated in favour of shiftheadinglevelby.

copyright
A document copyright (without the word “Copyright”), for example, “2017, Kristaps Dzonsons”.
Used in -Tms and -Thtml.

css A CSS file included in the HTML5 document head. Multiple CSS files (in order) may be separated
by two or more spaces (including newlines). Only used in -Thtml.

date Document date in ISO-8601 YYYY-MM-DD format. Overridden by rcsdate. Used in -Tfodt, -Thtml,
-Tlatex, -Tman, and -Tms.

javascript
A JavaScript file included in the HTML5 document head. Multiple script files (in order) may be
separated by two or more spaces (including newlines). Only used in -Thtml.

rcsauthor
Like author, but in RCS author format. Overrides author.

rcsdate
Like date, but in RCS date format. Overrides date.

section
Man page section, defaulting to “7”. Only used in -Tman.

shiftheadinglevelby
Shift all headers by the given number. For example, a value of 1 causes headers originally at
level 1 (“<h1>”) to be level 2 (“<h2>”), while a value of -1 moves level 2 to 1. Levels will not
move to less than 1. Takes precedence over baseheaderlevel. If unset or not a valid number,
defaults to zero. Used in -Tfodt, -Thtml, -Tlatex, -Tman, and -Tms.

source Man page source (organisation providing the manual). Only used in -Tman.

volume Man page volume (describes the manual page section). Only used in -Tman.

title Document title, defaulting to “Untitled article”. Used in -Tfodt, -Thtml, -Tlatex, -Tman, and
-Tms.

Metadata values are parsed and may be used as variables in markdown documents regardless of whether -s is
specified or not.

Default values, such “Untitled article” for the title, are not set as metadata values, and will not
appear if the metadata key is used as a variable.

Output modes
A detailed description of the output modes follows.

-Tlatex
“Flat” OpenDocument output. This output mode is still in development.

-Tgemini
Gemini protocol output. This output mode (and the protocol) are experimental.

-Thtml HTML5 output with UTF-8 encoding. All features of lowdown(5) are supported.

-Tlatex
Simple LaTeX output. The following packages are required: amsmath and amssymb for maths,
graphicx for images, inputenc (utf8) for UTF-8 input, fontend (T1) and textcomp for output
glyphs, lmodern for Latin modern font, xcolor for the difference engine output, and hyperref for
links.

-Tman The man macro package suitable for reading by groff(1), mandoc(1), or traditional troff(1). Does
not support equations and images. Table support is provided by tbl(1). Since UTF-8 may be
passed as input values, preconv(1) may need to be used.

-Tms The ms macro package suitable for reading by groff(1) or traditional troff(1). Does not support
equations and limited image support for encapsulated postscript (PS and EPS suffix) images.
Images are always block-formatted. Image dimensions and extended attributes are ignored, though
images are downsized if larger than the current text width. Table support is provided by tbl(1).
Since UTF-8 may be passed as input values, preconv(1) may need to be used.

-Tterm ANSI-escaped UTF-8 output suitable for reading on the terminal. Images and equations not
supported.

-Ttree Debugging output: not for general use.

Without -s specified, several of these modes will omit parts of the output:

-Tfodt Omit all but the <office:automatic-styles>, <office:master-styles>, and <office:body> elements
and their children.

-Thtml Omit all but the <body> element and its children.

-Tlatex
Omit the documentclass, usepackage, and surrounding begin{document} statements.

-Tman, -Tms
Omit the document prologue.

Output is augmented with features for viewing file differences. These depend upon the output mode.

-Tfodt Uses the change-tracking feature to display insertions and deletions.

-Tman, -Tms
When data has been removed, it is coloured red. When data has been inserted, it is coloured in
green. In either case, your formatter must support colours or the texts will be freely
intermingled.

-Thtml When data has been removed from the old document, it is marked up with the <del> element. When
data has been inserted into the new document, <ins> is used instead.

-Tlatex
When data has been removed, it is coloured red. When data has been inserted, it is coloured in
green.

-Tterm Removed and inserted data have different background colours.

ENVIRONMENT

       The following environment variables affect the execution of lowdown-diff:

       NO_COLOR
               Do not emit colours when in -Tterm mode.  Synonym for NO_COLOUR.  Same as --term-nocolour.

EXIT STATUS

       The lowdown-diff utility exits 0 on success, and >0 if an error occurs.

EXAMPLES

       To view Markdown differences on an ANSI-compatible, UTF-8 terminal:

             lowdown-diff -Tterm old.md new.md | less -R

       The terminal may also be used with groff(1) rendering:

             lowdown-diff -sTms old.md new.md | \
               groff -itk -mspdf -Tutf8 | less -R
             lowdown-diff -sTman old.md new.md | \
               groff -itk -man -Tutf8 | less -R

       To emit a standalone HTML5 document:

             lowdown-diff -s old.md new.md > foo.html

       To use groff(1) to format as a PS file:

             lowdown-diff -sTms old.md new.md | \
               groff -itk -mspdf > foo.ps

       Or with LaTeX:

             lowdown-diff -sTlatex old.md new.md > foo.latex
             pslatex foo.latex

       PDF generation follows similar logic:

             lowdown-diff -sTms old.md new.md | \
               pdfroff -itk -mspdf > foo.pdf
             lowdown-diff -sTlatex old.md new.md > foo.latex
             pdflatex foo.latex

       UTF-8 support for groff(1) PDF or PS output requires appropriate fonts, such as the Unicode  Times  font.
       This  and other Unicode fonts are not always installed by default.  They may be found, for PDF output, in
       the devpdf set of the groff(1) font directory and are prefixed with ‘U’.

             lowdown-diff -sTms old.md new.md | \
               pdfroff -itk -mspdf -FU-T > foo.pdf

AUTHORS

       lowdown-diff was written by Kristaps Dzonsons, kristaps@bsd.lv.

CAVEATS

       When viewing -Tman differences with mandoc, the marker colours are not  rendered.   The  -Tgemini  output
       also currently has no way of encoding differences.

Debian                                             $Mdocdate$                                    LOWDOWN-DIFF(1)