/usr/share/man : Manual pages
Purpose
This section details the organization for manual pages throughout the system, including /usr/share/man. Also refer to the section on /var/cache/man.
The primary <mandir> of the system is /usr/share/man. /usr/share/man contains manual information for commands and data under the / and /usr filesystems. [31]
Manual pages are stored in <mandir>/<locale>/man<section>/<arch>. An explanation of <mandir>, <locale>, <section>, and <arch> is given below.
A description of each section follows:
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man1: User programs Manual pages that describe publicly accessible commands are contained in this chapter. Most program documentation that a user will need to use is located here.
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man2: System calls This section describes all of the system calls (requests for the kernel to perform operations).
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man3: Library functions and subroutines Section 3 describes program library routines that are not direct calls to kernel services. This and chapter 2 are only really of interest to programmers.
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man4: Special files Section 4 describes the special files, related driver functions, and networking support available in the system. Typically, this includes the device files found in /dev and the kernel interface to networking protocol support.
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man5: File formats The formats for many data files are documented in the section 5. This includes various include files, program output files, and system files.
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man6: Games This chapter documents games, demos, and generally trivial programs. Different people have various notions about how essential this is.
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man7: Miscellaneous Manual pages that are difficult to classify are designated as being section 7. The troff and other text processing macro packages are found here.
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man8: System administration Programs used by system administrators for system operation and maintenance are documented here. Some of these programs are also occasionally useful for normal users.
Specific Options
The following directories, or symbolic links to directories, must be in /usr/share/<mandir>/<locale>, unless they are empty: [32]
| Directory | Description |
|---|---|
| man1 | User programs (optional) |
| man2 | System calls (optional) |
| man3 | Library calls (optional) |
| man4 | Special files (optional) |
| man5 | File formats (optional) |
| man6 | Games (optional) |
| man7 | Miscellaneous (optional) |
| man8 | System administration (optional) |
The component <section> describes the manual section.
Provisions must be made in the structure of /usr/share/man to support manual pages which are written in different (or multiple) languages. These provisions must take into account the storage and reference of these manual pages. Relevant factors include language (including geographical-based differences), and character code set.
This naming of language subdirectories of /usr/share/man is based on Appendix E of the POSIX 1003.1 standard which describes the locale identification string - the most well-accepted method to describe a cultural environment. The <locale> string is:
<language>[_<territory>][.<character-set>][,<version>]
The <language> field must be taken from ISO 639 (a code for the representation of names of languages). It must be two characters wide and specified with lowercase letters only.
The <territory> field must be the two-letter code of ISO 3166 (a specification of representations of countries), if possible. (Most people are familiar with the two-letter codes used for the country codes in email addresses.) It must be two characters wide and specified with uppercase letters only. [33]
The <character-set> field must represent the standard describing the character set. If the <character-set> field is just a numeric specification, the number represents the number of the international standard describing the character set. It is recommended that this be a numeric representation if possible (ISO standards, especially), not include additional punctuation symbols, and that any letters be in lowercase.
A parameter specifying a <version> of the profile may be placed after the <character-set> field, delimited by a comma. This may be used to discriminate between different cultural needs; for instance, dictionary order versus a more systems-oriented collating order. This standard recommends not using the <version> field, unless it is necessary.
Systems which use a unique language and code set for all manual pages may omit the <locale> substring and store all manual pages in <mandir>. For example, systems which only have English manual pages coded with ASCII, may store manual pages (the man<section> directories) directly in /usr/share/man. (That is the traditional circumstance and arrangement, in fact.)
Countries for which there is a well-accepted standard character code set may omit the <character-set> field, but it is strongly recommended that it be included, especially for countries with several competing standards.
Various examples:
| Language | Territory | Character Set | Directory |
|---|---|---|---|
| English | - | ASCII | /usr/share/man/en |
| English | United Kingdom | ISO 8859-15 | /usr/share/man/en_GB |
| English | United States | ASCII | /usr/share/man/en_US |
| French | Canada | ISO 8859-1 | /usr/share/man/fr_CA |
| French | France | ISO 8859-1 | /usr/share/man/fr_FR |
| German | Germany | ISO 646 | /usr/share/man/de_DE.646 |
| German | Germany | ISO 6937 | /usr/share/man/de_DE.6937 |
| German | Germany | ISO 8859-1 | /usr/share/man/de_DE.88591 |
| German | Switzerland | ISO 646 | /usr/share/man/de_CH.646 |
| Japanese | Japan | JIS | /usr/share/man/ja_JP.jis |
| Japanese | Japan | SJIS | /usr/share/man/ja_JP.sjis |
| Japanese | Japan | UJIS (or EUC-J) | /usr/share/man/ja_JP.ujis |
Similarly, provision must be made for manual pages which are architecture-dependent, such as documentation on device-drivers or low-level system administration commands. These must be placed under an <arch> directory in the appropriate man<section> directory; for example, a man page for the i386 ctrlaltdel(8) command might be placed in /usr/share/man/<locale>/man8/i386/ctrlaltdel.8.
Manual pages for commands and data under /usr/local are stored in /usr/local/man. Manual pages for X11R6 are stored in /usr/X11R6/man. It follows that all manual page hierarchies in the system must have the same structure as /usr/share/man.
The cat page sections (cat<section>) containing formatted manual page entries are also found within subdirectories of <mandir>/<locale>, but are not required nor may they be distributed in lieu of nroff source manual pages.
The numbered sections "1" through "8" are traditionally defined. In general, the file name for manual pages located within a particular section end with .<section>.
In addition, some large sets of application-specific manual pages have an additional suffix appended to the manual page filename. For example, the MH mail handling system manual pages must have mh appended to all MH manuals. All X Window System manual pages must have an x appended to the filename.
The practice of placing various language manual pages in appropriate subdirectories of /usr/share/man also applies to the other manual page hierarchies, such as /usr/local/man and /usr/X11R6/man. (This portion of the standard also applies later in the section on the optional /var/cache/man structure.)