Provided by: manpages_6.8-2_all bug

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)