= Generate Manual Pages from AsciiDoc
:navtitle: Generate Manual Pages
:url-man-page: https://en.wikipedia.org/wiki/Man_page
:url-man-7: https://man7.org/linux/man-pages/man7/roff.7.html
:url-docbook-refmisc: https://tdg.docbook.org/tdg/5.0/refmiscinfo.html
:url-asciidoctor-1-raw: https://raw.githubusercontent.com/asciidoctor/asciidoctor/v{release-version}/man/asciidoctor.adoc
:url-git-man: https://github.com/git/git/tree/master/Documentation

The AsciiDoc language defines a doctype named `manpage` for composing manual pages (man pages) in AsciiDoc.
Asciidoctor provides a converter for converting this AsciiDoc structure into a groff-formatted man page.
This page introduces **man**ual pages, examines the AsciiDoc structure of a man page, and shows how to convert an AsciiDoc document to groff-formatted man page and other formats using Asciidoctor.

== What's a manual page?

A {url-man-page}[manual page^], abbreviated as [.term]_man page_, is a form of software documentation that typically accompanies software on Unix-like operating systems.
Its formalized structure allows the `man` command to present the man page as a formatted document in a terminal pager, such as `less`.

The benefit of composing a man page in AsciiDoc is that you can convert it to multiple formats, including HTML and PDF.
That makes the source of the man page reusable.

[#doctype]
== manpage doctype

The `manpage` doctype declares that the AsciiDoc structure serves as the source of a man page and conforms to the man page structure.
Note the absence of the space in the doctype value.

By declaring the `manpage` doctype, the AsciiDoc processor expects the document to conform to the following structure.

Document Header::
In a man page, the document header is mandatory.
The doctitle consists of the program name followed by the volume number in round brackets (e.g., `progname(1)`).
The doctitle must not contain spaces.
The volume number is a single digit optionally followed by a single character.

Document Attributes::
There are several built-in document attributes that impact how the source is parsed and converted when the `manpage` doctype is in use.
Refer to the <<document-attributes>> section.

The NAME Section::
The first section is mandatory, must be titled "`Name`" (or "`NAME`"), and must contain a single paragraph (usually a single line) consisting of a list of one or more comma-separated command name(s) separated from the command's purpose by a dash character (e.g., `progname - does stuff` or `name1, name2 - does stuff`).
The dash must have at least one space character on either side.
If multiple names are given, Asciidoctor will generate alias files for the secondary names that point to the primary name.

The SYNOPSIS Section::
The second section is recommended and, if present, must be titled "`Synopsis`" (or "`SYNOPSIS`").

Subsequent sections are optional, but typical sections include "`Description`", "`Options`", "`Bugs`", "`See Also`", "`Copyright`", and "`Author`".
You can write the section titles in all uppercase, but it's better to let the man page converter handle that for you.
See <<generate>> for details.

TIP: Since the structure required by the `manpage` doctype is standard AsciiDoc, you can opt to declare the `manpage` doctype at runtime.
When the `doctype` attribute is not set, Asciidoctor will parse the document as an article and not give it any special treatment.

Here's an example man page composed in AsciiDoc for the `eve` command.
Observe that it declares the `manpage` doctype and conforms to the described structure.

.progname.adoc
[,asciidoc]
----
include::example$manpage.adoc[]
----

Although the source document is named [.path]_progname.adoc_, you can name the file whatever you like.
The output filename is determined by the `manname` and `manvolnum` attributes implicitly defined by the doctitle.
In this example, the output filename is [.path]_eve.1_.

== Backend and converter

Asciidoctor provides a built-in converter to generate {url-man-7}[groff-formatted^] man pages for AsciiDoc documents that declare the `manpage` doctype and conform to it.
Asciidoctor's own man page (i.e., `man asciidoctor`) is generated using this converter from {url-asciidoctor-1-raw}[this AsciiDoc source].

The man page converter is bound to the `manpage` backend (not to be confused with the `manpage` doctype).
Note the absence of the space in the backend value.

[horizontal]
Backend name:: `manpage`
Converter class:: `Asciidoctor::Converter::ManpageConverter`
Output format:: groff
Output file extension:: .\{manvolnum} (e.g., .1)

[#generate]
== Generate a man page

First, ensure your source document conforms to the <<doctype,manpage doctype structure>> and the `doctype` attribute is set to the value `manpage`.
Then, to activate the man page converter, you must assign `manpage` to the `backend` option.
Doing so will instruct the processor to use the man page converter to convert the document.

For the purpose of this example, we'll assue that the doctitle in [.path]_progname.adoc_ is `progname(1)`, where `progname` is the name of the command and `1` is the volume number.
Based on this information, the man page converter will set the output file name to [.path]_progname.1_.

To generate a man page, run:

 $ asciidoctor -b manpage progname.adoc

You can then view the resulting man page using the `man` command:

 $ man ./progname.1

When converting to the man page format, Asciidoctor uppercases the titles of all level-0 and level-1 sections.
This transformation is applied to conform to the widely adopted convention used by most man pages found on *nix systems.
By applying this transform in the converter, it saves you from having to type section titles in all uppercase in the source document.
It also makes the document portable to other output formats since this style is only needed for the man page output.
If the titles are uppercased in the source, that casing ends up getting used in all output formats.

CAUTION: Prior to Ruby 2.4, Ruby could only uppercase Latin letters.
If you're using Ruby 2.4 or greater, Asciidoctor will uppercase any letter in the title that's recognized by the Unicode specification as having an uppercase equivalent, which extends beyond Latin letters.

Recall that you're not limited to using the man page converter to convert an AsciiDoc document that uses the `manpage` doctype.
You can just as well convert it to HTML, as shown here.

 $ asciidoctor progname.adoc

The structure of the source document is still enforced, but the output document will look like the output of any other AsciiDoc document.

== Repurpose a man page

You may have a man page that you want to repurpose for documenting equivalent commands (but not aliases).
You can do so by supplying an alternate man title, name, and/or purpose when converting the document.

If you want to change `mantitle` and `manvolnum` attributes, you must override the `doctitle` attribute when invoking Asciidoctor.

 $ asciidoctor -b manpage -a doctitle="othername(7)" progname.adoc

This command sets the `mantitle` to "`othername`", the `manvolnum` to "`7`", and generates the file [.path]_progname.7_.
However, the `mantitle` is only used in the hidden info section at the top of the man page.
What you probably want to do is change the `manname` too, which is the name used in the header, the Name section, and the output filename.

One way to change the `manname` is to set both the `manname` and `manpurpose` attributes when calling Asciidoctor.
But first, you need to hide the default Name section in this case so you don't end up with two Name sections.

[,asciidoc]
----
\ifndef::manname,manpurpose[]
== Name

progname - description of progname
\endif::[]
----

Now, you can replace the information in the Name section when calling Asciidoctor:

 $ asciidoctor -b manpage \
   -a doctitle="othername(7)" \
   -a manname=othername \
   -a manpurpose="description of othername" \
   progname.adoc

This command generates the file [.path]_othername.7_.

If you only want to override the `manname` attribute and not the `manpurpose` attribute, reconfigure the Name section as shown in the next example.

[,asciidoc]
----
\ifndef::manname[:manname: progname]

== Name

{manname} - description of progname
----

Now, you can override the `manname` attribute without having to override the `manpurpose` attribute.

 $ asciidoctor -b manpage \
   -a doctitle="othername(7)" \
   -a manname=othername \
   progname.adoc

It's important to remember that Asciidoctor derives the `manname` and `manpurpose` attributes from the Name section by default.
That's why it's not enough just to override the attributes when calling Asciidoctor.

However, if you want to make a well-formed man page from a document that doesn't have a Name section, you can effectively insert one by setting the `manname` and `manpurpose` attributes from the CLI:

 $ asciidoctor -b manpage \
   -a doctitle="README(1)" \
   -a doctype=manpage \
   -a manname=README \
   -a manpurpose="Information about this project" \
   README.adoc

You can now view the README as a man page using the `man` command:

 man ./README.1

Just remember that a well-formed man page requires both a name and a purpose.

== Convert the man page to PostScript / PDF

Once you have created a man page, you can convert it to PostScript using the `man` command.

Let's assume that the output file produced by the Asciidoctor man page converter is `progname.1`, where `progname` is the name of the command and `1` is the volume number.
You can convert `progname.1` to PostScript and redirect the output to `progname.ps` using the following `man` command:

 $ man -t ./progname.1 > progname.ps

Alternately, you can redirect the output of the `man` command to `ps2pdf` to further convert it to PDF:

 $ man -t ./progname.1 | ps2pdf - progname.pdf

Let's now convert the example from earlier to PDF in this way:

 $ man -t ./eve.1 | ps2pdf - eve.pdf

Using the same sequence of commands, you can convert Asciidoctor's own man page to PDF:

 $ asciidoctor -h manpage | man -t -l - | ps2pdf - asciidoctor.pdf

In this case, the `-l -` reads the man page content generated by the help mode of the `asciidoctor` command.

Keep in mind that the files in this section are not generated using Asciidoctor.
If you want to generate PDF files directly from Asciidoctor, you may be interested in checking out https://github.com/asciidoctor/asciidoctor-pdf[Asciidoctor PDF^].
Another approach is to convert the AsciiDoc document to DocBook using the built-in DocBook converter (e.g., `-b docbook`), then convert that document to PDF using the DocBook toolchain.

[#document-attributes]
== Document attributes

Several built-in document attributes only affect the `manpage` doctype and output.
These attributes (or the attributes from which they are derived) must be set in the document header.

.Built-in document attributes for man pages
[%autowidth]
|===
|Attribute |Description |Value (as parsed from example above)

|`mantitle`
|Can be set by overriding the `doctitle` attribute.
Must include both the man page name and volume number.
|ASCIIDOCTOR(1)

|`manvolnum`
|Can be set by overriding the `doctitle` attribute.
Must include both the man page name and volume number.
|ASCIIDOCTOR(1)

|`manname`
|Alternative way to set the command name.
Only used if `manpurpose` is also set.
|asciidoctor

|`manpurpose`
|Alternative way to set the command purpose.
|converts AsciiDoc source files

|`man-linkstyle`
|Style the links in the man page output.
A valid link format sequence.
// Needs a reference to this.
|[.pre-wrap]#blue R < >#

|`mansource`
|The source to which the man page pertains.
When producing DocBook, it becomes a DocBook {url-docbook-refmisc}[refmiscinfo^] attribute and appears in the footer.
|Asciidoctor

|`manversion`
|The version of the man page.
Defaults to revnumber if not specified.
When producing DocBook, it becomes a DocBook {url-docbook-refmisc}[refmiscinfo^] attribute and appears in the footer.
Not used by Asciidoctor.
|{release-version}

|`manmanual`
|Manual name.
When producing DocBook, it becomes a DocBook {url-docbook-refmisc}[refmiscinfo^] attribute and appears in the footer.
|Asciidoctor Manual
|===

== See also

Refer to the {url-asciidoctor-1-raw}[AsciiDoc source of the Asciidoctor man page^] to see a complete example.
The man page for Asciidoctor is produced using the man page converter.
The {url-git-man}[man pages for git] are also produced from AsciiDoc documents, so you can use those as another example to follow.