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NAME

       man-pages - conventions for writing Linux man pages

SYNOPSIS

       man [section] title

DESCRIPTION

       This  page  describes  the  conventions that should be employed when writing man pages for the Linux man-
       pages project, which documents the user-space API provided by the Linux kernel and  the  GNU  C  library.
       The project thus provides most of the pages in Section 2, many of the pages that appear in Sections 3, 4,
       and 7, and a few of the pages that appear in Sections 1, 5, and 8 of the man pages  on  a  Linux  system.
       The  conventions  described  on  this  page  may  also  be useful for authors writing man pages for other
       projects.

   Sections of the manual pages
       The manual Sections are traditionally defined as follows:

       1 User commands (Programs)
              Commands that can be executed by the user from within a shell.

       2 System calls
              Functions which wrap operations performed by the kernel.

       3 Library calls
              All library functions excluding the system call wrappers (Most of the libc functions).

       4 Special files (devices)
              Files found in /dev which allow to access to devices through the kernel.

       5 File formats and configuration files
              Describes various human-readable file formats and configuration files.

       6 Games
              Games and funny little programs available on the system.

       7 Overview, conventions, and miscellaneous
              Overviews or descriptions of various topics, conventions, and protocols, character set  standards,
              the standard filesystem layout, and miscellaneous other things.

       8 System management commands
              Commands like mount(8), many of which only root can execute.

   Macro package
       New manual pages should be marked up using the groff an.tmac package described in man(7).  This choice is
       mainly for consistency: the vast majority of existing Linux  manual  pages  are  marked  up  using  these
       macros.

   Conventions for source file layout
       Please  limit  source code line length to no more than about 75 characters wherever possible.  This helps
       avoid line-wrapping in some mail clients when patches are submitted inline.

   Title line
       The first command in a man page should be a TH command:

              .TH title section date source manual-section

       The arguments of the command are as follows:

       title  The title of the man page, written in all caps (e.g., MAN-PAGES).

       section
              The section number in which the man page should be placed (e.g., 7).

       date   The date of the last nontrivial change that was made to  the  man  page.   (Within  the  man-pages
              project,  the necessary updates to these timestamps are handled automatically by scripts, so there
              is no need to manually update them as part of a patch.)  Dates should be written in the form YYYY-
              MM-DD.

       source The  name  and  version  of the project that provides the manual page (not necessarily the package
              that provides the functionality).

       manual-section
              Normally, this should be empty, since the default value will be good.

   Sections within a manual page
       The list below shows conventional or suggested sections.  Most manual pages should include at  least  the
       highlighted  sections.   Arrange  a new manual page so that sections are placed in the order shown in the
       list.

              NAME
              LIBRARY          [Normally only in Sections 2, 3]
              SYNOPSIS
              CONFIGURATION    [Normally only in Section 4]
              DESCRIPTION
              OPTIONS          [Normally only in Sections 1, 8]
              EXIT STATUS      [Normally only in Sections 1, 8]
              RETURN VALUE     [Normally only in Sections 2, 3]
              ERRORS           [Typically only in Sections 2, 3]
              ENVIRONMENT
              FILES
              ATTRIBUTES       [Normally only in Sections 2, 3]
              VERSIONS         [Normally only in Sections 2, 3]
              STANDARDS
              HISTORY
              NOTES
              CAVEATS
              BUGS
              EXAMPLES
              AUTHORS          [Discouraged]
              REPORTING BUGS   [Not used in man-pages]
              COPYRIGHT        [Not used in man-pages]
              SEE ALSO

       Where a traditional heading would apply, please use it; this kind of consistency can make the information
       easier  to  understand.   If  you  must,  you  can create your own headings if they make things easier to
       understand (this can be especially useful for pages in Sections 4 and 5).  However,  before  doing  this,
       consider  whether  you  could  use  the  traditional  headings,  with some subsections (.SS) within those
       sections.

       The following list elaborates on the contents of each of the above sections.

       NAME   The name of this manual page.

              See man(7) for important details of the line(s) that should follow  the  .SH  NAME  command.   All
              words  in  this  line  (including the word immediately following the "\-") should be in lowercase,
              except where English or technical terminological convention dictates otherwise.

       LIBRARY
              The library providing a symbol.

              It shows the common name of the library, and in parentheses, the name of the library file and,  if
              needed, the linker flag needed to link a program against it: (libfoo[, -lfoo]).

       SYNOPSIS
              A brief summary of the command or function's interface.

              For commands, this shows the syntax of the command and its arguments (including options); boldface
              is used for as-is text and italics are used to  indicate  replaceable  arguments.   Brackets  ([])
              surround  optional  arguments,  vertical  bars  (|)  separate  choices,  and ellipses (...) can be
              repeated.  For functions, it shows any required data declarations or #include directives, followed
              by the function declaration.

              Where  a feature test macro must be defined in order to obtain the declaration of a function (or a
              variable)  from  a  header  file,  then  the  SYNOPSIS  should  indicate  this,  as  described  in
              feature_test_macros(7).

       CONFIGURATION
              Configuration details for a device.

              This section normally appears only in Section 4 pages.

       DESCRIPTION
              An explanation of what the program, function, or format does.

              Discuss how it interacts with files and standard input, and what it produces on standard output or
              standard  error.   Omit  internals  and  implementation  details  unless  they're   critical   for
              understanding  the interface.  Describe the usual case; for information on command-line options of
              a program use the OPTIONS section.

              When describing new behavior or new flags for a system call or library  function,  be  careful  to
              note  the  kernel or C library version that introduced the change.  The preferred method of noting
              this information for flags is as part of a .TP list, in the following form (here, for a new system
              call flag):

                       XYZ_FLAG (since Linux 3.7)
                              Description of flag...

              Including  version  information  is  especially useful to users who are constrained to using older
              kernel or C library versions (which is typical in embedded systems, for example).

       OPTIONS
              A description of the command-line options accepted by a program and how they change its behavior.

              This section should appear only for Section 1 and 8 manual pages.

       EXIT STATUS
              A list of the possible exit status values of a program and the conditions that cause these  values
              to be returned.

              This section should appear only for Section 1 and 8 manual pages.

       RETURN VALUE
              For Section 2 and 3 pages, this section gives a list of the values the library routine will return
              to the caller and the conditions that cause these values to be returned.

       ERRORS For Section 2 and 3 manual pages, this is a list of the values that may be placed in errno in  the
              event of an error, along with information about the cause of the errors.

              Where  several  different  conditions  produce the same error, the preferred approach is to create
              separate list entries (with duplicate error names) for each of the  conditions.   This  makes  the
              separate  conditions  clear,  may  make the list easier to read, and allows metainformation (e.g.,
              kernel version number where the condition first became applicable) to be more  easily  marked  for
              each condition.

              The error list should be in alphabetical order.

       ENVIRONMENT
              A list of all environment variables that affect the program or function and how they affect it.

       FILES  A  list of the files the program or function uses, such as configuration files, startup files, and
              files the program directly operates on.

              Give the full pathname of these files, and use the installation process to  modify  the  directory
              part  to  match  user  preferences.   For  many  programs, the default installation location is in
              /usr/local, so your base manual page should use /usr/local as the base.

       ATTRIBUTES
              A summary of various attributes of the function(s) documented on this page.  See attributes(7) for
              further details.

       VERSIONS
              A summary of systems where the API performs differently, or where there's a similar API.

       STANDARDS
              A  description of any standards or conventions that relate to the function or command described by
              the manual page.

              The preferred terms to use for the various standards are listed as headings in standards(7).

              This section should note the current standards to which the API conforms to.

              If the API is not governed by any standards but commonly exists on other systems, note  them.   If
              the call is Linux-specific or GNU-specific, note this.  If it's available in the BSDs, note that.

              If  this section consists of just a list of standards (which it commonly does), terminate the list
              with a period ('.').

       HISTORY
              A brief summary of the Linux kernel or glibc versions where a  system  call  or  library  function
              appeared, or changed significantly in its operation.

              As  a  general  rule,  every  new  interface  should include a HISTORY section in its manual page.
              Unfortunately, many existing manual pages don't include  this  information  (since  there  was  no
              policy  to  do  so  when  they  were  written).  Patches to remedy this are welcome, but, from the
              perspective of programmers writing new code, this information probably matters only in the case of
              kernel  interfaces that have been added in Linux 2.4 or later (i.e., changes since Linux 2.2), and
              library functions that have been added to glibc since glibc 2.1 (i.e., changes since glibc 2.0).

              The syscalls(2) manual page also provides information  about  kernel  versions  in  which  various
              system calls first appeared.

       Old  versions  of  standards should be mentioned here, rather than in STANDARDS, for example, SUS, SUSv2,
       and XPG, or the SVr4 and 4.xBSD implementation standards.

       NOTES  Miscellaneous notes.

              For Section 2 and 3 man pages you may find it useful to include subsections (SS) named Linux Notes
              and glibc Notes.

              In  Section  2,  use  the heading C library/kernel differences to mark off notes that describe the
              differences (if any) between the C library wrapper function for a system call and the  raw  system
              call interface provided by the kernel.

       CAVEATS
              Warnings about typical user misuse of an API, that don't constitute an API bug or design defect.

       BUGS   A list of limitations, known defects or inconveniences, and other questionable activities.

       EXAMPLES
              One or more examples demonstrating how this function, file, or command is used.

              For details on writing example programs, see Example programs below.

       AUTHORS
              A list of authors of the documentation or program.

              Use  of  an AUTHORS section is strongly discouraged.  Generally, it is better not to clutter every
              page with a list of (over time potentially numerous) authors; if you write or significantly  amend
              a page, add a copyright notice as a comment in the source file.  If you are the author of a device
              driver and want to include an address for reporting bugs, place this under the BUGS section.

       REPORTING BUGS
              The man-pages project doesn't use a REPORTING  BUGS  section  in  manual  pages.   Information  on
              reporting  bugs  is  instead  supplied in the script-generated COLOPHON section.  However, various
              projects do use a REPORTING BUGS section.  It is recommended to place it  near  the  foot  of  the
              page.

       COPYRIGHT
              The  man-pages  project doesn't use a COPYRIGHT section in manual pages.  Copyright information is
              instead maintained in the page source.  In pages where this section is present, it is  recommended
              to place it near the foot of the page, just above SEE ALSO.

       SEE ALSO
              A  comma-separated  list  of  related  man  pages,  possibly  followed  by  other related pages or
              documents.

              The list should be ordered by section number and then alphabetically by name.   Do  not  terminate
              this list with a period.

              Where  the SEE ALSO list contains many long manual page names, to improve the visual result of the
              output, it may be useful to employ the .ad l (don't  right  justify)  and  .nh  (don't  hyphenate)
              directives.   Hyphenation  of  individual  page names can be prevented by preceding words with the
              string "\%".

              Given the distributed, autonomous nature of FOSS projects and their documentation, it is sometimes
              necessary—and  in  many  cases  desirable—that  the SEE ALSO section includes references to manual
              pages provided by other projects.

FORMATTING AND WORDING CONVENTIONS

       The following subsections note some details for preferred formatting and wording conventions  in  various
       sections of the pages in the man-pages project.

   SYNOPSIS
       Wrap the function prototype(s) in a .nf/.fi pair to prevent filling.

       In general, where more than one function prototype is shown in the SYNOPSIS, the prototypes should not be
       separated by blank lines.  However, blank lines (achieved using .P) may be added in the following cases:

       •  to separate long lists of function prototypes into related groups (see for example list(3));

       •  in other cases that may improve readability.

       In the SYNOPSIS, a long function prototype may  need  to  be  continued  over  to  the  next  line.   The
       continuation line is indented according to the following rules:

       (1)  If  there is a single such prototype that needs to be continued, then align the continuation line so
            that when the page is rendered on a fixed-width font device (e.g., on  an  xterm)  the  continuation
            line  starts  just  below  the  start  of  the  argument  list  in  the line above.  (Exception: the
            indentation may be adjusted if necessary to prevent a very  long  continuation  line  or  a  further
            continuation line where the function prototype is very long.)  As an example:

                int tcsetattr(int fd, int optional_actions,
                              const struct termios *termios_p);

       (2)  But,  where  multiple  functions  in the SYNOPSIS require continuation lines, and the function names
            have different lengths, then align all continuation  lines  to  start  in  the  same  column.   This
            provides  a  nicer  rendering  in  PDF output (because the SYNOPSIS uses a variable width font where
            spaces render narrower than most characters).  As an example:

                int getopt(int argc, char * const argv[],
                           const char *optstring);
                int getopt_long(int argc, char * const argv[],
                           const char *optstring,
                           const struct option *longopts, int *longindex);

   RETURN VALUE
       The preferred wording to describe how errno is set is "errno is set to indicate the  error"  or  similar.
       This wording is consistent with the wording used in both POSIX.1 and FreeBSD.

   ATTRIBUTES
       Note the following:

       •  Wrap  the  table  in  this  section  in a .ad l/.ad pair to disable text filling and a .nh/.hy pair to
          disable hyphenation.

       •  Ensure that the table occupies the full page width through the use of an lbx description  for  one  of
          the  columns  (usually  the first column, though in some cases the last column if it contains a lot of
          text).

       •  Make free use of T{/T} macro pairs to allow table cells to be broken over multiple lines (also bearing
          in mind that pages may sometimes be rendered to a width of less than 80 columns).

       For examples of all of the above, see the source code of various pages.

STYLE GUIDE

       The  following  subsections  describe  the  preferred  style  for the man-pages project.  For details not
       covered below, the Chicago Manual of Style is usually a good source; try also  grepping  for  preexisting
       usage in the project source tree.

   Use of gender-neutral language
       As  far  as  possible,  use  gender-neutral  language  in  the text of man pages.  Use of "they" ("them",
       "themself", "their") as a gender-neutral singular pronoun is acceptable.

   Formatting conventions for manual pages describing commands
       For manual pages that describe a command (typically in Sections  1  and  8),  the  arguments  are  always
       specified using italics, even in the SYNOPSIS section.

       The name of the command, and its options, should always be formatted in bold.

   Formatting conventions for manual pages describing functions
       For  manual  pages  that  describe  functions  (typically  in Sections 2 and 3), the arguments are always
       specified using italics, even in the SYNOPSIS section, where the rest of the  function  is  specified  in
       bold:

           int myfunction(int argc, char **argv);

       Variable names should, like argument names, be specified in italics.

       Any  reference to the subject of the current manual page should be written with the name in bold followed
       by a pair of parentheses in Roman (normal) font.  For example, in the fcntl(2) man  page,  references  to
       the subject of the page would be written as: fcntl().  The preferred way to write this in the source file
       is:

           .BR fcntl ()

       (Using this format, rather than the use of "\fB...\fP()" makes it easier to write tools  that  parse  man
       page source files.)

   Use semantic newlines
       In  the  source  of a manual page, new sentences should be started on new lines, long sentences should be
       split into lines at clause breaks (commas, semicolons, colons, and so on), and  long  clauses  should  be
       split  at phrase boundaries.  This convention, sometimes known as "semantic newlines", makes it easier to
       see the effect of patches, which often operate at the level of individual sentences, clauses, or phrases.

   Lists
       There are different kinds of lists:

       Tagged paragraphs
              These are used for a list of tags and their descriptions.  When the  tags  are  constants  (either
              macros or numbers) they are in bold.  Use the .TP macro.

              An example is this "Tagged paragraphs" subsection is itself.

       Ordered lists
              Elements  are  preceded  by a number in parentheses (1), (2).  These represent a set of steps that
              have an order.

              When there are substeps, they will be numbered like (4.2).

       Positional lists
              Elements are preceded by a number (index) in square brackets [4], [5].  These represent fields  in
              a set.  The first index will be:

              0      When it represents fields of a C data structure, to be consistent with arrays.
              1      When it represents fields of a file, to be consistent with tools like cut(1).

       Alternatives list
              Elements  are  preceded  by a letter in parentheses (a), (b).  These represent a set of (normally)
              exclusive alternatives.

       Bullet lists
              Elements are preceded by bullet symbols (\[bu]).  Anything that doesn't fit elsewhere  is  usually
              covered by this type of list.

       Numbered notes
              Not really a list, but the syntax is identical to "positional lists".

       There  should always be exactly 2 spaces between the list symbol and the elements.  This doesn't apply to
       "tagged paragraphs", which use the default indentation rules.

   Formatting conventions (general)
       Paragraphs should be separated by  suitable  markers  (usually  either  .P  or  .IP).   Do  not  separate
       paragraphs  using  blank  lines,  as  this  results  in  poor  rendering  in some output formats (such as
       PostScript and PDF).

       Filenames (whether pathnames, or references to header files) are always  in  italics  (e.g.,  <stdio.h>),
       except  in  the  SYNOPSIS  section,  where  included  files are in bold (e.g., #include <stdio.h>).  When
       referring to a standard header file include, specify the header file surrounded by angle brackets, in the
       usual C way (e.g., <stdio.h>).

       Special  macros,  which  are usually in uppercase, are in bold (e.g., MAXINT).  Exception: don't boldface
       NULL.

       When enumerating a list of error codes, the codes are in bold (this list usually uses the .TP macro).

       Complete commands should, if long, be written as an indented line on their own, with a blank line  before
       and after the command, for example

           man 7 man-pages

       If the command is short, then it can be included inline in the text, in italic format, for example, man 7
       man-pages.  In this case, it may be worth using nonbreaking spaces (\[ti])  at  suitable  places  in  the
       command.  Command options should be written in italics (e.g., -l).

       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.

       When showing example shell sessions, user input should be formatted in bold, for example

           $ date
           Thu Jul  7 13:01:27 CEST 2016

       Any reference to another man page should be written with the name in bold, always followed by the section
       number,  formatted in Roman (normal) font, without any separating spaces (e.g., intro(2)).  The preferred
       way to write this in the source file is:

           .BR intro (2)

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

       Control characters should be written in bold face, with no quotes; for example, ^X.

   Spelling
       Starting  with  release  2.59,  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:

       •  American  English  tends  to  use  the forms "backward", "upward", "toward", and so on rather than the
          British forms "backwards", "upwards", "towards", and so on.

       •  Opinions are divided on "acknowledgement" vs "acknowledgment".  The latter  is  predominant,  but  not
          universal usage in American English.  POSIX and the BSD license use the former spelling.  In the Linux
          man-pages project, we use "acknowledgement".

   BSD version numbers
       The classical scheme for writing BSD version numbers is x.yBSD, where x.y is the  version  number  (e.g.,
       4.2BSD).  Avoid forms such as BSD 4.3.

   Capitalization
       In  subsection  ("SS")  headings,  capitalize the first word in the heading, but otherwise use lowercase,
       except where English usage (e.g., proper nouns) or programming language  requirements  (e.g.,  identifier
       names) dictate otherwise.  For example:

           .SS Unicode under Linux

   Indentation of structure definitions, shell session logs, and so on
       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 .in +4n and .in), format  them  using  the  .EX  and  .EE  macros,  and
       surround them with suitable paragraph markers (either .P or .IP).  For example:

           .P
           .in +4n
           .EX
           int
           main(int argc, char *argv[])
           {
               return 0;
           }
           .EE
           .in
           .P

   Preferred terms
       The  following  table lists some preferred terms to use in man pages, mainly to ensure consistency across
       pages.

       Term                 Avoid using              Notes
       ──────────────────────────────────────────────────────────────────────
       bit mask             bitmask
       built-in             builtin
       Epoch                epoch                    For the UNIX Epoch
                                                     (00:00:00, 1 Jan 1970
                                                     UTC)
       filename             file name
       filesystem           file system
       hostname             host name
       inode                i-node
       lowercase            lower case, lower-case
       nonzero              non-zero
       pathname             path name
       pseudoterminal       pseudo-terminal
       privileged port      reserved port, system
                            port
       real-time            realtime, real time
       run time             runtime
       saved set-group-ID   saved group ID, saved
                            set-GID
       saved set-user-ID    saved user ID, saved
                            set-UID
       set-group-ID         set-GID, setgid
       set-user-ID          set-UID, setuid
       superuser            super user, super-user
       superblock           super block, super-
                            block
       symbolic link        symlink
       timestamp            time stamp
       timezone             time zone
       uppercase            upper case, upper-case
       usable               useable
       user space           userspace
       username             user name
       x86-64               x86_64                   Except if referring to
                                                     result of "uname -m"
                                                     or similar
       zeros                zeroes

       See also the discussion Hyphenation of attributive compounds below.

   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.

       Avoid             Use instead             Notes

       ───────────────────────────────────────────────────────────────────────

       32bit             32-bit                  same for 8-bit, 16-bit, etc.
       current process   calling process         A common mistake made by
                                                 kernel programmers when
                                                 writing man pages
       manpage           man page, manual page
       minus infinity    negative infinity
       non-root          unprivileged user
       non-superuser     unprivileged user
       nonprivileged     unprivileged
       OS                operating system
       plus infinity     positive infinity
       pty               pseudoterminal
       tty               terminal
       Unices            UNIX systems
       Unixes            UNIX systems

   Trademarks
       Use  the  correct  spelling and case for trademarks.  The following is a list of the correct spellings of
       various relevant trademarks that are sometimes misspelled:

              DG/UX
              HP-UX
              UNIX
              UnixWare

   NULL, NUL, null pointer, and null byte
       A null pointer is a pointer that points to nothing, and is normally indicated by the constant  NULL.   On
       the  other  hand,  NUL  is  the  null  byte,  a byte with the value 0, represented in C via the character
       constant '\0'.

       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".

   Hyperlinks
       For  hyperlinks, use the .UR/.UE macro pair (see 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

   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.",  "cf.",  and  "a.k.a."  should  be
       avoided,  in  favor of suitable full wordings ("for example", "that is", "and so on", "compare to", "also
       known as").

       The only place where such abbreviations may be acceptable is in 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.

   Em-dashes
       The way to write an em-dash—the glyph that appears at either end of this subphrase—in *roff is  with  the
       macro  "\[em]".   (On  an  ASCII  terminal,  an  em-dash  typically  renders as two hyphens, but in other
       typographical contexts it renders as a long dash.)   Em-dashes  should  be  written  without  surrounding
       spaces.

   Hyphenation of attributive compounds
       Compound  terms  should  be  hyphenated when used attributively (i.e., to qualify a following noun). Some
       examples:

              32-bit value
              command-line argument
              floating-point number
              run-time check
              user-space function

              wide-character string

   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.

   Generating optimal glyphs
       Where  a  real  minus  character is required (e.g., for numbers such as -1, for man page cross references
       such as utf-8(7), or when writing options that have a leading dash, such as in ls -l), use the  following
       form in the man page source:

           \-

       This guideline applies also to code examples.

       The use of real minus signs serves the following purposes:

       •  To  provide  better  renderings  on  various targets other than ASCII terminals, notably in PDF and on
          Unicode/UTF-8-capable terminals.

       •  To generate glyphs that when copied from rendered pages will produce real minus signs when pasted into
          a terminal.

       To  produce  unslanted  single quotes that render well in ASCII, UTF-8, and PDF, use "\[aq]" ("apostrophe
       quote"); for example

           \[aq]C\[aq]

       where C is the quoted character.  This guideline  applies  also  to  character  constants  used  in  code
       examples.

       Where  a proper caret (^) that renders well in both a terminal and PDF is required, use "\[ha]".  This is
       especially necessary in code samples, to get a nicely rendered caret when rendering to PDF.

       Using a naked "~" character results in a poor rendering in PDF.  Instead use "\[ti]".  This is especially
       necessary in code samples, to get a nicely rendered tilde when rendering to PDF.

   Example programs and shell sessions
       Manual  pages  may  include  example programs demonstrating how to use a system call or library function.
       However, note the following:

       •  Example programs should be written in C.

       •  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.

       •  Example programs should ideally be short (e.g., a good example can often be provided in less than  100
          lines  of  code), though in some cases longer programs may be necessary to properly illustrate the use
          of an API.

       •  Expressive code is appreciated.

       •  Comments should included where helpful.   Complete  sentences  in  free-standing  comments  should  be
          terminated  by  a  period.  Periods should generally be omitted in "tag" comments (i.e., comments that
          are placed on the same line of code); such comments are in any case  typically  brief  phrases  rather
          than complete sentences.

       •  Example programs should do error checking after system calls and library function calls.

       •  Example programs should be complete, and compile without warnings when compiled with cc -Wall.

       •  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).

       •  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!)  The following command can be used  to  format  your
          source code to something close to the preferred style:

              indent -npro -kr -i4 -ts4 -sob -l72 -ss -nut -psl prog.c

       •  For consistency, all example programs should 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;

       •  If there is extensive explanatory text before the program source code, mark off the source code with a
          subsection heading Program source, as in:

              .SS Program source

          Always do this if the explanatory text includes a shell session log.

       If you include a shell session log demonstrating the use of a program or other system feature:

       •  Place the session log above the source code listing.

       •  Indent the session log by four spaces.

       •  Boldface the user input text, to distinguish it from output produced by the system.

       For some examples of what example programs should look like, see wait(2) and pipe(2).

EXAMPLES

       For canonical examples of how man pages in the man-pages package should look, see pipe(2) and fcntl(2).

SEE ALSO

       man(1), man2html(1), attributes(7), groff(7), groff_man(7), man(7), mdoc(7)