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.\" Copyright (c) 2014, 2016 Ingo Schwarze <schwarze@openbsd.org>
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.Dd $Mdocdate$
.Dt MANDOC.DB 5
.Os
.Sh NAME
.Nm mandoc.db
.Nd manual page database
.Sh DESCRIPTION
The
.Nm
file format is used to store information about installed manual
pages to facilitate semantic searching for manuals.
Each manual page tree contains its own
.Nm
file; see
.Sx FILES
for examples.
.Pp
Such database files are generated by
.Xr makewhatis 8
and used by
.Xr man 1 ,
.Xr apropos 1
and
.Xr whatis 1 .
.Pp
The file format uses three datatypes:
.Pp
.Bl -dash -compact -offset 2n -width 1n
.It
32-bit signed integer numbers in big endian (network) byte ordering
.It
NUL-terminated strings
.It
lists of NUL-terminated strings, terminated by a second NUL character
.El
.Pp
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.
.Pp
Each file consists of:
.Pp
.Bl -dash -compact -offset 2n -width 1n
.It
One magic number, 0x3a7d0cdb.
.It
One version number, currently 1.
.It
One pointer to the macros table.
.It
One pointer to the final magic number.
.It
The pages table (variable length).
.It
The macros table (variable length).
.It
The magic number once again, 0x3a7d0cdb.
.El
.Pp
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:
.Pp
.Bl -dash -compact -offset 2n -width 1n
.It
The number of pages in the database.
.It
For each page:
.Bl -dash -compact -offset 2n -width 1n
.It
One pointer to the list of names.
.It
One pointer to the list of sections.
.It
One pointer to the list of architectures
or 0 if the page is machine-independent.
.It
One pointer to the one-line description string.
.It
One pointer to the list of filenames.
.El
.It
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:
.Bl -dash -compact -offset 2n -width 1n
.It
0x10: The name appears in a filename.
.It
0x08: The name appears in a header line, i.e. in a .Dt or .TH macro.
.It
0x04: The name is the first one in the title line, i.e. it appears
in the first .Nm macro in the NAME section.
.It
0x02: The name appears in any .Nm macro in the NAME section.
.It
0x01: The name appears in an .Nm block in the SYNOPSIS section.
.El
.It
For each page, the list of sections.
Each section is given as a string, not as a number.
.It
For each architecture-dependent page, the list of architectures.
.It
For each page, the one-line description string taken from the .Nd macro.
.It
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
.Xr roff 7
requests.
The first filename is preceded by a single byte
having the following significance:
.Bl -dash -compact -offset 2n -width 1n
.It
.Dv FORM_SRC No = 0x01 :
The file format is
.Xr mdoc 7
or
.Xr man 7 .
.It
.Dv FORM_CAT No = 0x02 :
The manual page is preformatted.
.El
.It
Zero to three NUL bytes for padding.
.El
.Pp
The macros table consists of:
.Pp
.Bl -dash -compact -offset 2n -width 1n
.It
The number of different macro keys, currently 36.
The ordering of macros is defined in
.In mansearch.h
and the significance of the macro keys is documented in
.Xr apropos 1 .
.It
For each macro key, one pointer to the respective macro table.
.It
For each macro key, the macro table (variable length).
.El
.Pp
Each macro table consists of:
.Pp
.Bl -dash -compact -offset 2n -width 1n
.It
The number of entries in the table.
.It
For each entry:
.Bl -dash -compact -offset 2n -width 1n
.It
One pointer to the value of the macro key.
Each value is a string of text taken from some macro invocation.
.It
One pointer to the list of pages.
.El
.It
For each entry, the value of the macro key.
.It
Zero to three NUL bytes for padding.
.It
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.
.El
.Sh FILES
.Bl -tag -width /usr/share/man/mandoc.db -compact
.It Pa /usr/share/man/mandoc.db
The manual page database for the base system.
.It Pa /usr/X11R6/man/mandoc.db
The same for the
.Xr X 7
Window System.
.It Pa /usr/local/man/mandoc.db
The same for
.Xr packages 7 .
.El
.Pp
A program to dump
.Nm
files in a human-readable format suitable for
.Xr diff 1
is provided in the directory
.Pa /usr/src/regress/usr.bin/mandoc/db/dbm_dump/ .
.Sh SEE ALSO
.Xr apropos 1 ,
.Xr man 1 ,
.Xr whatis 1 ,
.Xr makewhatis 8
.Sh HISTORY
A manual page database
.Pa /usr/lib/whatis
first appeared in
.Bx 2 .
The present format first appeared in
.Ox 6.1 .
.Sh AUTHORS
.An -nosplit
The original version of
.Xr makewhatis 8
was written by
.An Bill Joy
in 1979.
The present database format was designed by
.An Ingo Schwarze Aq Mt schwarze@openbsd.org
in 2016.
