Beginnings of a style guide

Hello all,

One of the things that's long been on my list is to create a style guide for man pages, which gives style guidelines on some common issues specific to writing man pages. Prompted my Mike Frysinger, I've made a start by including a STYLE GUIDE section in man-pages(7). Comment, suggested improvements, and so on, welcome.

Cheers,

Michael

(The complete page source can be found in git,
https://www.kernel.org/doc/man-pages/download.html )

.SH STYLE GUIDE
The following subsections represent the beginnings of a style guide for the
.IR "man-pages"
project.
For details not covered below, the Chicago Manual of Style is usually a good source.
.SS Use of gender-neutral language
As far as possible, use gender-neutral language in the text of man page.
Use of "they" ("them", "themself", "their") as a gender-neutral singular pronoun is acceptable for pages in the
.IR man-pages
project.
.SS Font conventions
.PP
For functions, the arguments are always specified using italics, .IR "even in the SYNOPSIS section" ,
where the rest of the function is specified in bold:
.PP
.BI " int myfunction(int " argc ", char **" argv );
.PP
Variable names should, like argument names, be specified in italics. .PP
Filenames (whether pathnames, or references to files in the .I /usr/include
directory)
are always in italics (e.g.,
.IR <stdio.h> ),
except in the SYNOPSIS section, where included files are in bold (e.g., .BR "#include <stdio.h>" ).
When referring to a standard include file under
.IR /usr/include ,
specify the header file surrounded by angle brackets,
in the usual C way (e.g.,
.IR <stdio.h> ).
.PP
Special macros, which are usually in upper case, are in bold (e.g., .BR MAXINT ).
Exception: don't boldface NULL.
.PP
When enumerating a list of error codes, the codes are in bold (this list usually uses the
.B \&.TP
macro).
.PP
Complete commands should, if long,
be written as an indented line on their own, for example
.in +4n
.nf

man 7 man-pages

.fi
.in
If the command is short, then it can be included inline in the text, in italic format, for example,
.IR "man 7 man-pages" .
In this case, it may be worth using nonbreaking spaces ("\e\ ") at suitable places in the command.
Command options should be written in italics (e.g.,
.IR \-l ).
.PP
Expressions, if not written on a separate indented line, should be specified in italics.
Again, the use of nonbreaking spaces may be appropriate if the expression is inlined with normal text.
.PP
Any reference to the subject of the current manual page should be written with the name in bold.
If the subject is a function (i.e., this is a Section 2 or 3 page), then the name should be followed by a pair of parentheses in Roman (normal) font.
For example, in the
.BR fcntl (2)
man page, references to the subject of the page would be written as:
.BR fcntl ().
The preferred way to write this in the source file is:
.nf

.BR fcntl ()

.fi
(Using this format, rather than the use of "\\fB...\\fP()" makes it easier to write tools that parse man page source files.) .PP
Any reference to another man page
should be written with the name in bold,
.I always
followed by the section number,
formatted in Roman (normal) font, without any separating spaces (e.g.,
.BR intro (2)).
The preferred way to write this in the source file is:
.nf

    .BR intro (2)

.fi
(Including the section number in cross references lets tools like .BR man2html (1)
create properly hyperlinked pages.)

Control characters should be written in bold face,
with no quotes; for example,
.BR ^X .
.SS Spelling
Starting with release 2.59,
.I man-pages
follows American spelling conventions
(previously, there was a random mix of British and American spellings); please write all new pages and patches according to these conventions.

Aside from the well-known spelling differences,
there are a few other subtleties to watch for:
.IP * 3
American English tends to use the forms "backward" "upward", 'toward", and so on
rather than the British forms "backwards", upwards", "towards", and so on. .SS BSD version numbers
The classical scheme for writing BSD version numbers is
.IR x.yBSD ,
where
.I x.y
is the version number (e.g., 4.2BSD).
Avoid forms such as
.IR "BSD 4.3" .
.SS Capitalization
In subsection ("SS") headings,
capitalize the first word in the heading, but otherwise use lower case, except where English usage (e.g., proper nouns) or programming language requirements (e.g., identifier names) dictate otherwise. .SS Indentation of structure definitions, shell session logs, etc. When structure definitions, shell session logs, and so on are included in running text, indent them by 4 spaces (i.e., a block enclosed by .I ".in\ +4n"
and
.IR ".in" ).
.SS Preferred terms
The following table lists some preferred terms to use in man pages, mainly to ensure consistency across pages.
.ad l
.TS
l l l
---
l l l.
Term Avoid using Notes

bit mask bitmask
built-in builtin
Epoch epoch T{
For the UNIX Epoch (00:00:00, 1 Jan 1970 UTC)
T}
filename file name
hostname host name
inode i-node
pathname path name
pseudoterminal pseudo-terminal
privileged port T{
reserved port,
system port
T}
real-time T{
realtime,
real-time
T}
run time runtime
saved set-group-ID T{
saved group ID,
saved set-GID
T}
saved set-user-ID T{
saved user ID,
saved set-UID
T}
set-group-ID set-GID, setgid
set-user-ID set-UID, setuid
superuser T{
super user,
super-user
T}
timestamp time stamp
timezone time zone
user space userspace
username user name
zeros zeroes
.TE
.ad
.SS Terms to avoid
The following table lists some terms to avoid using in man pages, along with some suggested alternatives,
mainly to ensure consistency across pages.
.ad l
.TS
l l l
---
l l l.
Avoid Use instead Notes

current process calling process T{
A common mistake made by kernel programmers when writing man pages T}
manpage T{
man page, manual page
T}
minus infinity negative infinity
non-root unprivileged user
non-superuser unprivileged user
nonprivileged unprivileged
OS operating system
plus infinity positive infinity
pty pseudoterminal
runtime run time
tty terminal
Unices UNIX systems
Unixes UNIX systems
.TE
.ad
.SS Trademarks
Use the correct spelling of trademarks.
The following is a list of the correct spelling of various relevant trademarks that are sometimes misspelled:

DG/UX
HP-UX
UNIX
UnixWare
.SS NULL, NUL, null pointer, and null character
A
.IR "null pointer"
is a pointer that points to nothing,
and is normally indicated by the constant
.IR NULL .
On the other hand,
.I NUL
is the
.IR "null byte",
a byte with the value 0, represented in C via the character constant .IR \(aq\e0\(aq .

The preferred term for the pointer is "null pointer" or simply "NULL"; avoid writing "NULL pointer".

The preferred term for the byte is "null byte".
Avoid writing "NUL", since it is too easily confused with "NULL". Avoid also the terms "zero byte" and "null character". The byte that terminates a C string should be described as "the terminating null byte";
strings may be described as "null-terminated",
but avoid the use of "NUL-terminated".
.SS Hyperlinks
For hyperlinks, use the
.IR .UR / .UE
macro pair
(see
.BR groff_man (7)).
This produces proper hyperlinks that can be used in a web browser, when rendering a page with, say:

BROWSER=firefox man -H pagename
.SS Use of e.g., i.e., etc., a.k.a., and similar
In general, the use of abbreviations such as "e.g.", "i.e.", "etc.", "a.k.a." should be avoided, in favor of suitable full wordings
("for example", "that is", "and so on", "also known as").

The only place where such abbreviations may be acceptable is in .I short
parenthetical asides (e.g., like this one).

Always include periods in such abbreviations, as shown here. In addition, "e.g." and "i.e." should always be followed by a comma. .SS Em-dashes
The way to write an em-dash (\(em) in *roff is with the macro "\\(em". Em-dashes should be written
.I without
surrounding spaces.
.SS Hyphenation of attributive compounds
Counpound terms should by hyphenated when used attributively (i.e., to qualify a following noun) Some examples:

command-line argument
floating-point number
run-time check
user-space function
wide-character string
.SS Hyphenation with multi, non, pre, re, sub, and so on The general tendency in modern English is not to hyphenate after prefixes such as "multi", "non", "pre", "re", "sub", and so on. Manual pages should generally follow this rule when these prefixes are used in natural English constructions with simple suffixes. The following list gives some examples of the preferred forms:

interprocess
multithreaded
multiprocess
nonblocking
nondefault
nonempty
noninteractive
nonnegative
nonportable
nonzero
preallocated
precreate
prerecorded
reestablished
reinitialize
rearm
reread
subcomponent
subdirectory
subsystem

Hyphens should be retained when the prefixes are used in nonstandard English words, with trademarks, proper nouns, acronyms, or compound terms. Some examples:

non-ASCII
non-English
non-NULL
non-real-time

Finally, note that "re-create" and "recreate" are two different verbs, and the former is probably what you want.
.SS Real hyphen character
Where a real hyphen character is required (e.g., for numbers such as \-1), use the following form in the man page source

    \\-

This guideline applies also to code examples.
.SS Character constants
To produce single quotes that render well in both ASCII and UTF-8, use the following form for character constants in the man page source:

    \\(aqC\\(aq

where
.I C
is the quoted character.
This guideline applies also to character constants used in code examples. .SS Example programs and shell sessions
Manual pages can include example programs demonstrating how to use a system call or library function.
However, note the following:
.IP * 3
Example programs should be written in C.
.IP *
An example program is necessary and useful only if it demonstrates something beyond what can easily be provided in a textual description of the interface.
An example program that does nothing
other than call an interface usually serves little purpose. .IP *
Example programs should be fairly short (preferably less than 100 lines; ideally less than 50 lines).
.IP *
Example programs should do error checking after system calls and library function calls.
.IP *
Example programs should be complete, and compile without warnings when compiled with \fIcc\ \-Wall\fP.
.IP *
Where possible and appropriate, example programs should allow experimentation, by varying their behavior based on inputs (ideally from command-line arguments, or alternatively, via input read by the program).
.IP *
Example programs should be laid out according to Kernighan and Ritchie style, with 4-space indents.
(Avoid the use of TAB characters in source code!)
.IP *
For consistency, all example programs terminate using either of;

     exit(EXIT_SUCCESS);
     exit(EXIT_FAILURE);

Avoid using the following forms to terminate a program:

    exit(0);
    exit(1);
    return n;

.IP *
If there is extensive explanatory text before the
program source code, mark off the source code
with a susbsection heading
.IR "Program source" ,
as in:

.SS Program source

Always do this if the explanatory text includes a shell session log. .PP
If you include a shell session log demonstrating the use of a program or other system feature:
.IP * 3
Place the session log above the source code listing
.IP *
Indent the session log by four spaces.
.IP *
Boldface the user input text,
to distinguish it from output produced by the system.
.PP
For some examples of what example programs should look like, see .BR wait (2)
and
.BR pipe (2).

Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[ Resending as text/pain. Sorry for this. ]

Hi,

really nice. Especially for non-native speakers. One typo below:

Compounds terms

Thanks.

Bert
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html

Thanks. (Just "Compound terms though.)

Actually, two typos in that line! s/by/be/

Cheers,

Michael

Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

these are the kind of time based sentences that hang around for years ;)

how about:

	The following subsections describe the preferred style for the
	.IR "man-pages"
	project.

also, is that quoting really necessary ? and should the - be escaped ? you don't do it below, and the style guide seems to indicate you should :)

would also add a suggestion of grepping around for pre-existing usage in the tree.

page->pages ?

do we really need to mention the man-pages project again ? seems superfluous here.

where->while ?

add a .PP for casts ?

how about discussing spacing ? none before the argument list, but there should be one between a cast and the casted object.

i wonder if we should say something like "a standard library include" rather than explicitly listing "/usr/include". after all, some headers are provided by the C compiler (and likely won't be in /usr/include), and that path isn't applicable when talking about cross-compilers or user-based installs, or other not-quite-as-funky setups. we could retain one mention of /usr/include in an aside like "(e.g. headers in /usr/include)".

should also mention that there should be a blank line before/after it. otherwise, this code would pass the guide:

Complete commands ...
.br
man 7 man-pages

is "Roman" really necessary here ? it's not like changing fonts is even feasible in man pages.

there's a stray single quote before the toward rather than double quote

might be useful to include an example here

how about:

	32-bit	32bit	Also applies to 64-bit/128-bit/etc...
	filesystem	file system, fs

the run time/user space/etc... items could do with a note pointing to the hyphenation section below

would be nice to have a sentence on the preferred wording when talking about an empty C string (i.e. "").

how about also discouraging use of lists like "this/that/other/etc..." in favor of "this, that, other, and so on"

would be nice to add an example of what this is replacing as not everyone knows what an "em dash" is.

can->may
-mike

Yes, better. Changed.

No; fixed.

No. Maybe I need to clarify something. In general, the only time you need a real dash is for numbers and pieces of code.

Done.

Already fixed.

Removed.

"where" seems better to me.

I might add this later.

Yup. Made some changes here.

Done.

Here the distinction is "Roman" versus "Italic". It's the term used by the "man" macros.

Thanks,

I added

.SS Unicode under Linux

as an example

Added.

Added.

I added a reference to that section.

Do you have a suggested wording?

It's rarely been a problem, so I'm loathe to clutter the list with that guideline (but I agree with it).

Done.

Done.

Thanks for checking this over, Mike.

Updated version is in Git.

Cheers,

Michael

Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html