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Aman page (short formanual page) is a form ofsoftware documentation found onUnix andUnix-likeoperating systems. Topics covered include programs,system libraries,system calls, and sometimes local system details. The local host administrators can create and install manual pages associated with the specific host. A manual end user may invoke a documentation page by issuing themancommand followed by the name of the item for which they want the documentation. These manual pages are typically requested by end users, programmers and administrators doing real time work but can also be formatted for printing.
By default,man typically uses a formatting program such asnroff with a macro package ormandoc, and also aterminal pager program such asmore orless to display its output on the user's screen.
Man pages are often referred to as anonline form of software documentation,[1] even though theman command does not require internet access. The environment variable MANPATH often specifies a list of directory paths to search for the various documentation pages. Manual pages date back to the times when printed documentation was the norm.
Before Unix (e.g.,GCOS), documentation was printed pages, available on the premises to users (staff, students...), organized into steel binders, locked together in one monolithic steel reading rack, bolted to a table or counter, with pages organized for modular information updates, replacement, errata, and addenda.[citation needed]
In the first two years of thehistory of Unix, no documentation existed.[2] TheUnix Programmer's Manual was first published on November 3, 1971. The first actual man pages were written byDennis Ritchie andKen Thompson at the insistence[citation needed] of their managerDoug McIlroy in 1971. Aside from the man pages, theProgrammer's Manual also accumulated a set of short papers, some of themtutorials (e.g. for general Unix usage, theC programming language, and tools such asYacc), and others more detailed descriptions of operating system features. The printed version of the manual initially fit into a single binder, but as ofPWB/UNIX and the7th Edition ofResearch Unix, it was split into two volumes with the printed man pages forming Volume 1.[3]
Later versions of the documentation imitated the first man pages' terseness. Ritchie added a "How to get started" section to theThird Edition introduction, andLorinda Cherry provided the "Purple Card" pocket reference for theSixth andSeventh Editions.[2] Versions of the software were named after the revision of the manual; the seventh edition of theUnix Programmer's Manual, for example, came with the 7th Edition or Version 7 of Unix.[4]
For theFourth Edition the man pages were formatted using thetroff typesetting package[2] and its set of-man macros (which were completely revised between the Sixth and Seventh Editions of theManual,[3] but have since not drastically changed). At the time, the availability of online documentation through the manual page system was regarded as a great advance. To this day, virtually every Unix command line application comes with a man page, and many Unix users perceive a program's lack of man pages as a sign of low quality or incompleteness. Indeed, some projects, such asDebian, go out of their way to write man pages for programs lacking one. The modern descendants of4.4BSD also distribute man pages as one of the primary forms of system documentation (having replaced the old-man macros with the newer-mdoc).
There was a hiddenEaster egg in the man-db version of the man command that would cause the command to return "gimme gimme gimme" when run at 00:30 (a reference to theABBA songGimme! Gimme! Gimme! (A Man After Midnight). It was introduced in 2011[5] but first restricted[6] and then removed in 2017[7] after finally being found.[8]
The default format of man pages istroff, with either themacro package man (appearance oriented) or mdoc (semantic oriented). This makes it possible to typeset a man page intoPostScript,PDF, and various other formats for viewing or printing.
SomeUnix systems have a package for theman2html command, which enables users to browse their man pages using an HTML browser. Systems with groff and man-db should use the higher-quality native HTML output (man --html) instead.TheGNU Emacs programWoMan (from "WithOut man") allows to browse man pages from the editor.[9]
In 2010,OpenBSD deprecatedtroff for formatting man pages in favour ofmandoc, a specialised compiler/formatter for man pages with native support for output inPostScript,HTML,XHTML, and the terminal. It is meant to only support a subset of troff used in manual pages, specifically those using mdoc macros.
Quite a few websites offer online access to manual pages from various Unix-like systems.
In February 2013, theBSD community saw a new open sourcemdoc.su service launched, which unified and shortened access to the man.cgi scripts of the major modern BSD projects through a uniquenginx-based deterministicURL shortening service for the *BSD man pages.[10][11][12]
For Linux, a man7.org service has been set up to serve manuals specific to the system.[13] A ManKier service provides a wider selection, and integrates the TLDR pages too.[14]
To read a manual page for a Unix command, a user can type:
man<command_name>
Pages are traditionally referred to using the notation "name(section)": for example,ftp(1). The section refers to different ways the topic might be referenced - for example, as a system call, or a shell (command line) command or package, or a package's configuration file, or as a coding construct / header.
The same page name may appear in more than one section of the manual, such as when the names ofsystem calls, usercommands, ormacro packages coincide. Examples areman(1) andman(7), orexit(2) andexit(3). The syntax for accessing the non-default manual section varies between different man implementations.
On Solaris and illumos, for example, the syntax for readingprintf(3C) is:
man-s3cprintfOn Linux and BSD derivatives the same invocation would be:
man3printf
which searches forprintf in section 3 of the man pages. The actual file name likely includes the section. Continuing this example, printf.3.gz would be a compressed manual page file in section 3 forprintf.
The manual is generally split into eight numbered sections. Most systems today (e.g.BSD,[15]macOS,Linux,[16] andSolaris 11.4) inherit the numbering scheme used byResearch Unix.[17][18] WhileSystem V uses a different order:[19]
| Common | System V | Description |
|---|---|---|
| 1 | 1 | Generalcommands |
| 2 | 2 | System calls |
| 3 | 3 | Library functions, covering in particular theC standard library |
| 4 | 7 | Special files (usually devices, those found in /dev) anddrivers |
| 5 | 4 | File formats and conventions |
| 6 | 6 | Games andscreensavers |
| 7 | 5 | Miscellaneous |
| 8 | 1M | System administrationcommands anddaemons |
POSIX APIs are present in both sections 2 and 3, where section 2 contains APIs that are implemented as system calls and section 3 contains APIs that are implemented as library routines.
On some systems, additional sections may be included such as:
| Section | Description |
|---|---|
| 0 | C libraryheader files (Unix v6) |
| 9 | Kernel routines (FreeBSD, SVR4, Linux)[18][15] |
| l | LAPACK library functions[20] |
| n | Tcl/Tk commands |
| x | TheX Window System |
Some sections are further subdivided by means of a suffix; for example, in some systems, section 3C is for C library calls, 3M is for the math library, and so on. A consequence of this is that section 8 (system administration commands) is sometimes relegated to the 1M subsection of the main commands section. Some subsection suffixes have a general meaning across sections:
| Subsection | Description |
|---|---|
| p | POSIX specifications |
| x | X Window System documentation |
(Section 3 tends to be the exception with the many suffixes for different languages.)
Some versions ofman cache the formatted versions of the last several pages viewed. One form is thecat page, simply piped to the pager for display.
All man pages follow a common layout that is optimized for presentation on a simpleASCII text display, possibly without any form of highlighting or font control. Sections present may include:[21]: MANUAL STRUCTURE
Other sections may be present, but these are not well standardized across man pages. Common examples include: OPTIONS, EXIT STATUS, RETURN VALUE, ENVIRONMENT, BUGS, FILES, AUTHOR, REPORTING BUGS, HISTORY and COPYRIGHT.
Manual pages can be written either in the oldman macros, the newdoc macros, or a combination of both (mandoc).[22] Theman macro set provides minimalrich text functions, with directives for the title line, section headers, (bold, small or italic) fonts, paragraphs and adding/reducing indentation.[23] The newermdoc language is more semantic in nature, and contains specialized macros for most standard sections such as program name, synopsis, function names, and the name of the authors. This information can be used to implement asemantic search for manuals by programs such asmandoc. Although it also includes directives to directly control the styling, it is expected that the specialized macros will cover most of the use-cases.[21] Both the mandoc and the groff projects considermdoc the preferred format for new documents.[24]
Although man pages are, to troff, text laid out using 10-pointRoman type, this distinction is usually moot because man pages are viewed in the terminal (TTY) instead of laid out on paper. As a result, the "small font" macro is seldom used.[25] On the other hand, bold and italic text is supported by the terminal viaECMA-48, and groff'sgrotty does emit them as requested when it detects a supporting terminal. The BSD mandoc however only supports bold and underlined (as a replacement for italics) text via the typewriter backspace-then-overstrike sequence, which needs to be translated into ECMA-48 byless.[26][27]
Some tools have been used to convert documents in a less contrived format to manual pages. Examples include GNU'shelp2man, which takes a--help output and some additional content to generate a manual page.[28] The manual would be barely more useful than the said output, but for GNU programs this is not an issue as texinfo is the main documentation system.[29] A number of tools, includingpandoc, ronn, and md2man support conversion fromMarkdown to manual pages. All these tools emit theman format, as Markdown is not expressive enough to match the semantic content ofmdoc.DocBook has an inbuilt man(7) converter – of appalling quality, according to mandoc's author[30] who wrote a separate mdoc(7) converter.
Man pages are usually written in English, but translations into other languages may be available on the system. The GNUman-db and the mandocman is known to search for localized manual pages under subdirectories.[31][16]: Overview [15]
Few alternatives toman have enjoyed much popularity, with the possible exception ofGNU Project's "info" system, an early and simplehypertext system. There is also a third-party effort known asTLDR pages (tldr) that provides simple examples for common use cases, similar to acheatsheet.[32]
In addition, some UnixGUI applications (particularly those built using theGNOME andKDE development environments) now provide end-user documentation inHTML and include embedded HTML viewers such asyelp for reading the help within the application. An HTML system inEmacs is also slated to replace texinfo.[33]
infoaproposman(1) – FreeBSD General CommandsManualman(1) – Linux General CommandsManualmdoc(7) – FreeBSD Miscellaneous InformationManualgroff_tmac(5) – Linux File FormatsManualman(7) – Linux MiscellaneaManualConcurrent with work on man(7), mdoc(7) will be actively supported and its use promoted.
mandoc(1) – FreeBSD General CommandsManual. "Font styles are applied by using back-spaced encoding..."
| File system | |
|---|---|
| Processes | |
| User environment | |
| Text processing | |
| Shell builtins | |
| Searching | |
| Documentation | |
| Software development | |
| Miscellaneous | |
