Filesystem Hierarchy Standard

This section details the organization for manual pages throughout the system, including /usr/share/man. Also refer to the section on /var/cache/man.

Manual pages are stored in <mandir>/<locale>/man<section>/<arch>. An explanation of <mandir>, <locale>, <section>, and <arch> is given below.

"<mandir>/<locale>" man1 man2 man3 man4 man5 man6 man7 man8

"A manual page hierarchy" User programs System calls Library calls Special files File formats Games Miscellaneous System administration

Tree 4.7.2.1

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. Obviously, there are no manual pages in / because they are not required at boot time nor are they required in emergencies.

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 shall be taken from ISO 639 (a code for the representation of names of languages). It shall be two characters wide and specified with lowercase letters only.

The <territory> field shall 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 shall be two characters wide and specified with uppercase letters only. (A major exception to this rule is the United Kingdom, which is `GB' in the ISO 3166, but `UK' for most email addresses.)

The <character-set> field should 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 English English French French German German German German Japanese Japanese Japanese	-- United Kingdom United States Canada France Germany Germany Germany Switzerland Japan Japan Japan	ASCII ASCII ASCII ISO 8859-1 ISO 8859-1 ISO 646 ISO 6937 ISO 8859-1 ISO 646 JIS SJIS UJIS (or EUC-J)	/usr/share/man/en /usr/share/man/en_GB /usr/share/man/en_US /usr/share/man/fr_CA /usr/share/man/fr_FR /usr/share/man/de_DE.646 /usr/share/man/de_DE.6937 /usr/share/man/de_DE.88591 /usr/share/man/de_CH.646 /usr/share/man/ja_JP.jis /usr/share/man/ja_JP.sjis /usr/share/man/ja_JP.ujis

Table 4.7.2.1

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 should 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 should have the same structure as /usr/share/man. Empty directories may be omitted from a manual page hierarchy. For example, if /usr/local/man has no manual pages in section 4 (Devices), then /usr/local/man/man4 may be omitted.

The cat page sections (cat<section>) containing formatted manual page entries are also found within subdirectories of <mandir>/<locale>, but are not required nor should 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 should have mh appended to all MH manuals. All X Window System manual pages should 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.)

A description of each section follows:

• 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.
• man2: System calls
  This section describes all of the system calls (requests for the kernel to perform operations).
• 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.
• 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.
• man5: File formats
  The formats for many nonintuitive data files are documented in the section 5. This includes various include files, program output files, and system files.
• man6: Games
  This chapter documents games, demos, and generally trivial programs. Different people have various notions about how essential this is.
• 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.
• 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.