MD009 - Trailing spaces

Tags: whitespace

Aliases: no-trailing-spaces

Parameters: br_spaces (number; default: 0)

This rule is triggered on any lines that end with whitespace. To fix this, find the line that is triggered and remove any trailing spaces from the end.

The brspaces parameter allows an exception to this rule for a specific amount of trailing spaces used to insert an explicit line break/br element. For example, set brspaces to 2 to allow exactly 2 spaces at the end of a line.

Note: you have to set brspaces to 2 or higher for this exception to take effect - you can't insert a br element with just a single trailing space, so if you set brspaces to 1, the exception will be disabled, just as if it was set to the default of 0.

MD003 - Header style

Tags: headers

Aliases: header-style

Parameters: style ("consistent", "atx", "atxclosed", "setext", "setextwith_atx"; default "consistent")

This rule is triggered when different header styles (atx, setext, and 'closed' atx) are used in the same document:

# ATX style H1

## Closed ATX style H2 ##

Setext style H1
===============

Be consistent with the style of header used in a document:

# ATX style H1

## ATX style H2

The setextwithatx doc style allows atx-style headers of level 3 or more in documents with setext style headers:

Setext style H1
===============

Setext style H2
---------------

### ATX style H3

Note: the configured header style can be a specific style to use (atx, atxclosed, setext, setextwith_atx), or simply require that the usage be consistent within the document.

Limit all lines to a maximum of 79 characters.

There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to
have several windows side-by-side.  The default wrapping on such
devices looks ugly.  Therefore, please limit all lines to a maximum
of 79 characters. For flowing long blocks of text (docstrings or
comments), limiting the length to 72 characters is recommended.

Reports error E501.

Limit all lines to a maximum of 79 characters.

There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to
have several windows side-by-side.  The default wrapping on such
devices looks ugly.  Therefore, please limit all lines to a maximum
of 79 characters. For flowing long blocks of text (docstrings or
comments), limiting the length to 72 characters is recommended.

Reports error E501.

Never use the characters 'l', 'O', or 'I' as variable names.

In some fonts, these characters are indistinguishable from the
numerals one and zero. When tempted to use 'l', use 'L' instead.

Okay: L = 0
Okay: o = 123
Okay: i = 42
E741: l = 0
E741: O = 123
E741: I = 42

Variables can be bound in several other contexts, including class
and function definitions, 'global' and 'nonlocal' statements,
exception handlers, and 'with' and 'for' statements.
In addition, we have a special handling for function parameters.

Okay: except AttributeError as o:
Okay: with lock as L:
Okay: foo(l=12)
Okay: for a in foo(l=12):
E741: except AttributeError as O:
E741: with lock as l:
E741: global I
E741: nonlocal l
E741: def foo(l):
E741: def foo(l=12):
E741: l = foo(l=12)
E741: for l in range(10):
E742: class I(object):
E743: def l(x):

MD002 - First header should be a top level header

Tags: headers

Aliases: first-header-h1

Parameters: level (number; default 1)

This rule is triggered when the first header in the document isn't a h1 header:

## This isn't a H1 header

### Another header

The first header in the document should be a h1 header:

# Start with a H1 header

## Then use a H2 for subsections

MD003 - Header style

Tags: headers

Aliases: header-style

Parameters: style ("consistent", "atx", "atxclosed", "setext", "setextwith_atx"; default "consistent")

This rule is triggered when different header styles (atx, setext, and 'closed' atx) are used in the same document:

# ATX style H1

## Closed ATX style H2 ##

Setext style H1
===============

Be consistent with the style of header used in a document:

# ATX style H1

## ATX style H2

The setextwithatx doc style allows atx-style headers of level 3 or more in documents with setext style headers:

Setext style H1
===============

Setext style H2
---------------

### ATX style H3

Note: the configured header style can be a specific style to use (atx, atxclosed, setext, setextwith_atx), or simply require that the usage be consistent within the document.

MD003 - Header style

Tags: headers

Aliases: header-style

Parameters: style ("consistent", "atx", "atxclosed", "setext", "setextwith_atx"; default "consistent")

This rule is triggered when different header styles (atx, setext, and 'closed' atx) are used in the same document:

# ATX style H1

## Closed ATX style H2 ##

Setext style H1
===============

Be consistent with the style of header used in a document:

# ATX style H1

## ATX style H2

The setextwithatx doc style allows atx-style headers of level 3 or more in documents with setext style headers:

Setext style H1
===============

Setext style H2
---------------

### ATX style H3

Note: the configured header style can be a specific style to use (atx, atxclosed, setext, setextwith_atx), or simply require that the usage be consistent within the document.

MD003 - Header style

Tags: headers

Aliases: header-style

Parameters: style ("consistent", "atx", "atxclosed", "setext", "setextwith_atx"; default "consistent")

This rule is triggered when different header styles (atx, setext, and 'closed' atx) are used in the same document:

# ATX style H1

## Closed ATX style H2 ##

Setext style H1
===============

Be consistent with the style of header used in a document:

# ATX style H1

## ATX style H2

The setextwithatx doc style allows atx-style headers of level 3 or more in documents with setext style headers:

Setext style H1
===============

Setext style H2
---------------

### ATX style H3

Note: the configured header style can be a specific style to use (atx, atxclosed, setext, setextwith_atx), or simply require that the usage be consistent within the document.

Limit all lines to a maximum of 79 characters.

There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to
have several windows side-by-side.  The default wrapping on such
devices looks ugly.  Therefore, please limit all lines to a maximum
of 79 characters. For flowing long blocks of text (docstrings or
comments), limiting the length to 72 characters is recommended.

Reports error E501.

Limit all lines to a maximum of 79 characters.

There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to
have several windows side-by-side.  The default wrapping on such
devices looks ugly.  Therefore, please limit all lines to a maximum
of 79 characters. For flowing long blocks of text (docstrings or
comments), limiting the length to 72 characters is recommended.

Reports error E501.

Limit all lines to a maximum of 79 characters.

There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to
have several windows side-by-side.  The default wrapping on such
devices looks ugly.  Therefore, please limit all lines to a maximum
of 79 characters. For flowing long blocks of text (docstrings or
comments), limiting the length to 72 characters is recommended.

Reports error E501.

MD014 - Dollar signs used before commands without showing output

Tags: code

Aliases: commands-show-output

This rule is triggered when there are code blocks showing shell commands to be typed, and the shell commands are preceded by dollar signs ($):

$ ls
$ cat foo
$ less bar

The dollar signs are unnecessary in the above situation, and should not be included:

ls
cat foo
less bar

However, an exception is made when there is a need to distinguish between typed commands and command output, as in the following example:

$ ls
foo bar
$ cat foo
Hello world
$ cat bar
baz

Rationale: it is easier to copy and paste and less noisy if the dollar signs are omitted when they are not needed. See http://www.cirosantilli.com/markdown-styleguide/#dollar-signs-in-shell-code for more information.

Limit all lines to a maximum of 79 characters.

There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to
have several windows side-by-side.  The default wrapping on such
devices looks ugly.  Therefore, please limit all lines to a maximum
of 79 characters. For flowing long blocks of text (docstrings or
comments), limiting the length to 72 characters is recommended.

Reports error E501.

Never use the characters 'l', 'O', or 'I' as variable names.

In some fonts, these characters are indistinguishable from the
numerals one and zero. When tempted to use 'l', use 'L' instead.

Okay: L = 0
Okay: o = 123
Okay: i = 42
E741: l = 0
E741: O = 123
E741: I = 42

Variables can be bound in several other contexts, including class
and function definitions, 'global' and 'nonlocal' statements,
exception handlers, and 'with' and 'for' statements.
In addition, we have a special handling for function parameters.

Okay: except AttributeError as o:
Okay: with lock as L:
Okay: foo(l=12)
Okay: for a in foo(l=12):
E741: except AttributeError as O:
E741: with lock as l:
E741: global I
E741: nonlocal l
E741: def foo(l):
E741: def foo(l=12):
E741: l = foo(l=12)
E741: for l in range(10):
E742: class I(object):
E743: def l(x):

MD022 - Headers should be surrounded by blank lines

Tags: headers, blank_lines

Aliases: blanks-around-headers

This rule is triggered when headers (any style) are either not preceded or not followed by a blank line:

# Header 1
Some text

Some more text
## Header 2

To fix this, ensure that all headers have a blank line both before and after (except where the header is at the beginning or end of the document):

# Header 1

Some text

Some more text

## Header 2

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse headers that don't have a blank line before, and will parse them as regular text.

MD031 - Fenced code blocks should be surrounded by blank lines

Tags: code, blank_lines

Aliases: blanks-around-fences

This rule is triggered when fenced code blocks are either not preceded or not followed by a blank line:

Some text
```
Code block
```

```
Another code block
```
Some more text

To fix this, ensure that all fenced code blocks have a blank line both before and after (except where the block is at the beginning or end of the document):

Some text

```
Code block
```

```
Another code block
```

Some more text

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse fenced code blocks that don't have blank lines before and after them.

Limit all lines to a maximum of 79 characters.

There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to
have several windows side-by-side.  The default wrapping on such
devices looks ugly.  Therefore, please limit all lines to a maximum
of 79 characters. For flowing long blocks of text (docstrings or
comments), limiting the length to 72 characters is recommended.

Reports error E501.

Limit all lines to a maximum of 79 characters.

There are still many devices around that are limited to 80 character
lines; plus, limiting windows to 80 characters makes it possible to
have several windows side-by-side.  The default wrapping on such
devices looks ugly.  Therefore, please limit all lines to a maximum
of 79 characters. For flowing long blocks of text (docstrings or
comments), limiting the length to 72 characters is recommended.

Reports error E501.

MD003 - Header style

Tags: headers

Aliases: header-style

Parameters: style ("consistent", "atx", "atxclosed", "setext", "setextwith_atx"; default "consistent")

This rule is triggered when different header styles (atx, setext, and 'closed' atx) are used in the same document:

# ATX style H1

## Closed ATX style H2 ##

Setext style H1
===============

Be consistent with the style of header used in a document:

# ATX style H1

## ATX style H2

The setextwithatx doc style allows atx-style headers of level 3 or more in documents with setext style headers:

Setext style H1
===============

Setext style H2
---------------

### ATX style H3

Note: the configured header style can be a specific style to use (atx, atxclosed, setext, setextwith_atx), or simply require that the usage be consistent within the document.