mandoc.db — manual
page database
The mandoc.db file format is used to store
information about installed manual pages to facilitate semantic searching
for manuals. Each manual page tree contains its own
mandoc.db file; see
FILES for examples.
Such database files are generated by
makewhatis(8) and used by
man(1),
apropos(1) and
whatis(1).
The file format uses three datatypes:
- 32-bit signed integer numbers in big endian (network) byte ordering
- NUL-terminated strings
- lists of NUL-terminated strings, terminated by a second NUL character
Numbers are aligned to four-byte boundaries; where they follow
strings or lists of strings, padding with additional NUL characters occurs.
Some, but not all, numbers point to positions in the file. These pointers
are measured in bytes, and the first byte of the file is considered to be
byte 0.
Each file consists of:
- One magic number, 0x3a7d0cdb.
- One version number, currently 1.
- One pointer to the macros table.
- One pointer to the final magic number.
- The pages table (variable length).
- The macros table (variable length).
- The magic number once again, 0x3a7d0cdb.
The pages table contains one entry for each physical manual page
file, no matter how many hard and soft links it may have in the file system.
The pages table consists of:
- The number of pages in the database.
- For each page:
- One pointer to the list of names.
- One pointer to the list of sections.
- One pointer to the list of architectures or 0 if the page is
machine-independent.
- One pointer to the one-line description string.
- One pointer to the list of filenames.
- For each page, the list of names. Each name is preceded by a single byte
indicating the sources of the name. The meaning of the bits is:
- 0x10: The name appears in a filename.
- 0x08: The name appears in a header line, i.e. in a .Dt or .TH
macro.
- 0x04: The name is the first one in the title line, i.e. it appears in
the first .Nm macro in the NAME section.
- 0x02: The name appears in any .Nm macro in the NAME section.
- 0x01: The name appears in an .Nm block in the SYNOPSIS section.
- For each page, the list of sections. Each section is given as a string,
not as a number.
- For each architecture-dependent page, the list of architectures.
- For each page, the one-line description string taken from the .Nd
macro.
- For each page, the list of filenames relative to the root of the
respective manpath. This list includes hard links, soft links, and links
simulated with .so roff(7) requests. The
first filename is preceded by a single byte having the following
significance:
- Zero to three NUL bytes for padding.
The macros table consists of:
- The number of different macro keys, currently 36. The ordering of macros
is defined in
<mansearch.h> and the
significance of the macro keys is documented in
apropos(1).
- For each macro key, one pointer to the respective macro table.
- For each macro key, the macro table (variable length).
Each macro table consists of:
- The number of entries in the table.
- For each entry:
- One pointer to the value of the macro key. Each value is a string of
text taken from some macro invocation.
- One pointer to the list of pages.
- For each entry, the value of the macro key.
- Zero to three NUL bytes for padding.
- For each entry, one or more pointers to pages in the pages table, pointing
to the pointer to the list of names, followed by the number 0.
- /usr/share/man/mandoc.db
- The manual page database for the base system.
- /usr/X11R6/man/mandoc.db
- The same for the X(7) Window System.
- /usr/local/man/mandoc.db
- The same for packages(7).
A program to dump mandoc.db files in a
human-readable format suitable for diff(1)
is provided in the directory
/usr/src/regress/usr.bin/mandoc/db/dbm_dump/.
A manual page database /usr/lib/whatis
first appeared in 2BSD. The present format first
appeared in OpenBSD 6.1.