13.3. Markup

Various markup forms and rendering programs have been used for manual pages. FreeBSD has used groff(7) and the newer mandoc(1). Most existing FreeBSD manual pages, and all new ones, use the mdoc(7) form of markup. This is a simple line-based markup that is reasonably expressive. It is mostly semantic: parts of text are marked up for what they are, rather than for they should appear when rendered. There is some appearance-based markup which is usually best avoided.

Manual page source is usually interpreted and displayed to the screen interactively. The source files can be ordinary text files or compressed with gzip(1) to save space.

Manual pages can also be rendered to other formats, including PostScript for printing or PDF generation. See man(1).

Tip:

Testing a new manual page can be challenging when it is not located in the normal manual page search path. man(1) also does not look in the current directory. If the new manual page is in the current directory, prefix the filename with a ./:

% man ./mynewmanpage.8

An absolute path can also be used:

% man /home/xsmith/mynewmanpage.8

13.3.1. Manual Page Sections

Manual pages are composed of several standard sections. Each section has a title in upper case, and the sections for a particular type of manual page appear in a specific order. For a category 1 General Command manual page, the sections are:

Section NameDescription
NAMEName of the command
SYNOPSISFormat of options and arguments
DESCRIPTIONDescription of purpose and usage
ENVIRONMENTEnvironment settings that affect operation
EXIT STATUSError codes returned on exit
EXAMPLESExamples of usage
COMPATIBILITYCompatibility with other implementations
SEE ALSOCross-reference to related manual pages
STANDARDSCompatibility with standards like POSIX
HISTORYHistory of implementation
BUGSKnown bugs
AUTHORSPeople who created the command or wrote the manual page.

Some sections are optional, and the combination of sections for a specific type of manual page vary. Examples of the most common types are shown later in this chapter.

13.3.2. Macros

mdoc(7) markup is based on macros. Lines that begin with a dot contain macro commands, each two or three letters long. For example, consider this portion of the ls(1) manual page:

.Dd December 1, 2015  1
.Dt LS 1
.Sh NAME  2
.Nm ls
.Nd list directory contents
.Sh SYNOPSIS  3
.Nm  4
.Op Fl -libxo  5
.Op Fl ABCFGHILPRSTUWZabcdfghiklmnopqrstuwxy1,  6
.Op Fl D Ar format  7
.Op Ar  8
.Sh DESCRIPTION  9
For each operand that names a
.Ar file
of a type other than
directory,
.Nm
displays its name as well as any requested,
associated information.
For each operand that names a
.Ar file
of type directory,
.Nm
displays the names of files contained
within that directory, as well as any requested, associated
information.

1

A Document date and Document title are defined.

2

A Section header for the NAME section is defined. Then the Name of the command and a one-line Name description are defined.

3

The SYNOPSIS section begins. This section describes the command-line options and arguments accepted.

4

Name (.Nm) has already been defined, and repeating it here just displays the defined value in the text.

5

An Optional Flag called -libxo is shown. The Fl macro adds a dash to the beginning of flags, so this appears in the manual page as --libxo.

6

A long list of optional single-character flags are shown.

7

An optional -D flag is defined. If the -D flag is given, it must be followed by an Argument. The argument is a format, a string that tells ls(1) what to display and how to display it. Details on the format string are given later in the manual page.

8

A final optional argument is defined. Because no name is specified for the argument, the default of file ... is used.

9

The Section header for the DESCRIPTION section is defined.

When rendered with the command man ls, the result displayed on the screen looks like this:

LS(1)                   FreeBSD General Commands Manual                  LS(1)

NAME
     ls — list directory contents

SYNOPSIS
     ls [--libxo] [-ABCFGHILPRSTUWZabcdfghiklmnopqrstuwxy1,] [-D format]
        [file ...]

DESCRIPTION
     For each operand that names a file of a type other than directory, ls
     displays its name as well as any requested, associated information.  For
     each operand that names a file of type directory, ls displays the names
     of files contained within that directory, as well as any requested,
     associated information.

Optional values are shown inside square brackets.

13.3.3. Markup Guidelines

The mdoc(7) markup language is not very strict. For clarity and consistency, the FreeBSD Documentation project adds some additional style guidelines:

Only the first letter of macros is upper case

Always use upper case for the first letter of a macro and lower case for the remaining letters.

Begin new sentences on new lines

Start a new sentence on a new line, do not begin it on the same line as an existing sentence.

Update .Dd when making non-trivial changes to a manual page

The Document date informs the reader about the last time the manual page was updated. It is important to update whenever non-trivial changes are made to the manual pages. Trivial changes like spelling or punctuation fixes that do not affect usage can be made without updating .Dd.

Give examples

Show the reader examples when possible. Even trivial examples are valuable, because what is trivial to the writer is not necessarily trivial to the reader. Three examples are a good goal. A trivial example shows the minimal requirements, a serious example shows actual use, and an in-depth example demonstrates unusual or non-obvious functionality.

Include the BSD license

Include the BSD license on new manual pages. The preferred license is available from the Committer's Guide.

13.3.4. Markup Tricks

Add a space before punctuation on a line with macros. Example:

.Sh SEE ALSO
.Xr geom 4 ,
.Xr boot0cfg 8 ,
.Xr geom 8 ,
.Xr gptboot 8

Note how the commas at the end of the .Xr lines have been placed after a space. The .Xr macro expects two parameters to follow it, the name of an external manual page, and a section number. The space separates the punctuation from the section number. Without the space, the external links would incorrectly point to section 4, or 8,.

13.3.5. Important Macros

Some very common macros will be shown here. For more usage examples, see mdoc(7), groff_mdoc(7), or search for actual use in /usr/share/man/man* directories. For example, to search for examples of the .Bd Begin display macro:

% find /usr/share/man/man* | xargs zgrep '.Bd'

13.3.5.1. Organizational Macros

Some macros are used to define logical blocks of a manual page.

Organizational MacroUse
.ShSection header. Followed by the name of the section, traditionally all upper case. Think of these as chapter titles.
.SsSubsection header. Followed by the name of the subsection. Used to divide a .Sh section into subsections.
.BlBegin list. Start a list of items.
.ElEnd a list.
.BdBegin display. Begin a special area of text, like an indented area.
.EdEnd display.

13.3.5.2. Inline Macros

Many macros are used to mark up inline text.

Inline MacroUse
.NmName. Called with a name as a parameter on the first use, then used later without the parameter to display the name that has already been defined.
.PaPath to a file. Used to mark up filenames and directory paths.

All FreeBSD documents are available for download at https://download.freebsd.org/ftp/doc/

Questions that are not answered by the documentation may be sent to <freebsd-questions@FreeBSD.org>.
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